- M -

machete (n) – A large, heavy-bladed knife used for cutting down sugar cane or dense underbrush, especially in Central or South America

macro (adj) – Not needing the aid of a microscope in order to be seen

macroalgae (n) – Large aquatic photosynthetic plants that can been seen without the aid of a microscope

macroalgal (adj) – Consisting of macroalgae

macroinvertabrate (n) – An animal that has no backbone and can be seen without the aid of a microscope

made off (v) – See "make fast"

maggot (n) – A wormlike insect larva; some maggots are found in decaying matter

magma (n) – Molten rock under the earth’s crust, from which igneous rock is formed

magnate (n) – A very important and influential person in any field of activity, but particularly in a large business

magnetic north (n) – The direction towards which a magnetic needle points

magnitude (n) – Greatness in significance or influence

main traveler (n) – A traveler on the main sail

mainmast (n) – The principal and largest mast aboard a vessel

mainsail (n) – The largest sail on the ship

main salon (n) – 1 : The main social cabin of a passenger ship 2 : The sitting or dining area on a boat or ship; also called the "saloon"

main saloon (n) – 1 : The main social cabin of a passenger ship  2 : The sitting or dining area on a boat or ship; also called the "salon"

mainsheet (n) – A line or rope on a boat that controls the angle at which the mainsail is set to the wind

main-topsail (n) – A sail set on the main-topmast above the mainsail

"make fast" (v) – In nautical terms, to firmly fasten or secure

makeshift (adj) – Refers to a temporary solution; a solution that "will do" for a while; something used or assembled as a temporary or expedient substitute

malaria (n) – A human disease, caused by parasites, that is characterized by periodic attacks of chills and fevers; it is transmitted by certain species of mosquito

mandated (adj) – Made mandatory, as by law; required

mandatory (adj) – Required or commanded by authority; obligatory

maneuvers (n) – Military training exercises involving the movement of troops or naval

mangal (n) – A dense mangrove forest or swamp

mangrove (n) – 1 : One of several species of coastal, aquatic, tropical trees that form large colonies in swamps or shallow waters  2 : The swampy habitat in which such trees grow

manta tow (n) – A board pulled behind a moving boat, used by researchers to perform rapid visual surveys of underwater environments

maraca (n) – A percussion instrument consisting of a dried gourd or gourd-shaped rattle with dried seeds or loose pebbles inside, shaken to beat out a rhythm

marathon (n) – A footrace of 26 miles, 385 yards

Mardi Gras (n) – The last day before Lent, characterized by celebration and carnival, often marking the climax of a carnival period; also called Fat Tuesday or Shrove Tuesday

marginal (adj) – Barely within a lower standard or limit of quality

Mariana Trench (n) – The deepest area of the ocean, estimated at 11,033 meters (36,198 feet) in depth

marina (n) – A small harbor or boat basin where dockage, supplies, fuel, etc. are supplied

marine (adj) – Of the sea or ocean

Marine No-Take Reserve (MNTR) (n) – A marine area in which fishing is illegal

Marine Protected Area (MPA) (n) – An area protected from environmental damage by the regulation and restriction of human activities

mariner (n) – A sailor or seaman

Mariner’s Watch (n) – A traditional watch on board a ship in which each watch group stands watch for a 4-hour period; watches change at 0000 hours, 0400 hours, 0800 hours, 1200 hours, 1600 hours, and 2000 hours

maritime (adj) – Relating to anything on or near the sea

market niche (n) – A specialized part of an economy or market

marsupial (n) – Common name for any of a large group of mammals lacking a placenta, many of which carry and nourish their young in an abdominal pouch after birth (i.e. kangaroo)

Masai (n) – A member of a people of Kenya and parts of Tanzania

mass (n) – A quantity of matter forming a body of indefinite shape and size (though often large)

mast (n) – A pole, yard, or strong, piece of timber that is set upright in a boat and that holds the sails and rigging

matriarch (n) – A female who dominates and leads a family or group

maturation (n) – The act or process of becoming fully grown

mature (adj) – Fully grown or developed

maturity (n) – The state of being fully grown or developed

maximum sustainable yield (MSY) (n) – In a fishery, the total catch humans can take from a fish population without damaging its ability to recover

mean (adj) – Average

meander (v) – To wind around or wander through

meander (n) – Circuitous windings, as of a stream or path

measuring wheel (n) – A piece of field equipment designed to measure distances; generally composed of a small wheel and calibrated meter mounted on the end of a handle

mecca (n) – A center of activity sought by people sharing a common interest; literally, Mecca is a holy destination of Islamic pilgrims located in Saudi Arabia

mediate (v) – To act as arbitrator between two people or sides of an argument

medina (n) – An Arab marketplace

medium (n) – A surrounding or enveloping substance

melancholy (adj) – Tending to promote sadness or gloom

membrane (n) – A thin sheet or layer of substance which serves as a covering or lining

mentor (n) – A teacher or coach

meridian (n) – A circle around the earth which passes through both geographical poles and any given point on the earth’s surface; another name for a line of longitude; the Prime Meridian is the world’s longitudinal reference point

mesmerize (v) – To hypnotize; to amaze

Mesoamerica (n) – The region including Mexico, Central America and the northern sections of South America; two of the most famous ancient Mesoamerican cultures were the Mayans and Aztecs

mess (n) – Dining hall on a ship

metabolic functions (n) – The process by which organisms convert nutrients into energy

metabolize (v) – To change by or be subject to metabolism, the physical and chemical processes continuously going on in living organisms and cells

metaphor (n) – A figure of speech in which a word or phrase ordinarily and primarily used to describe one thing is applied to another

metamorphic rock (n) – A type of rock that has been changed by pressure, heat, chemical action, etc.

metamorphosis (n) – A transformation, as if by magic or sorcery

meteorology (n) – The science of weather

meteorologist (n) – Someone who studies the science of weather

meteorologically (adv) – With respect to the weather

methodology (n) – A body of practices, procedures, and rules used by those who work in a discipline or engage in an inquiry; a set of working methods

meticulous (adj) – Extremely detail-oriented; extremely careful and precise; excessively concerned with details

metropolis (n) – A large city or center of population and culture

microclimate (n) – A climate of a small, distinct area or confined space

microhabitat (n) – A very small, specialized habitat, such as a clump of grass or a space between rocks

microhylids (n) – Narrow-mouthed frogs found in South America, Africa, Madagascar, SE Asia, Indonesia, New Guinea, and northeastern Australia. In many microhylids, the body from is tear-drop-shaped, with a narrow, pointed snout and rather rounded body.

microsilica (n) – Tiny grains of silica, a hard glassy mineral

midden (n) – A garbage heap

Middle Passage (n) – The voyage from Africa to the United States that slave traders made in the 1600s to 1800s

midships (adj) – At the midpoint of a ship, roughly halfway between the stem and stern, where the beam usually is the widest

migrate (v) – To move from one place to another

migration (n) – The act of moving from one location to another

migratory (adj) – Moving from one place to another

Milky Way (n) – The spiral galaxy containing our sun; seen from Earth as a broad, faintly luminous band of stars and gas which arches across the night sky

mimic (v) – To imitate

mimicry (n) – A superficial resemblance of one organism to another or to natural objects among which it lives

minaret (n) – A tall slender tower of a mosque having at least one balcony from which the summons to prayer is cried by the muezzin

mirage (n) – Something that falsely appears to be real

mist net (n) – A net consisting of thin filaments, used to capture birds for research; the benefits of this type of net include the facts that they are hard to see and that they do not harm the birds

mizzen (adj) – Of the mizzenmast

mizzenmast (n) – Aboard the three-masted Concordia, the aft most of the three

moai (n) – The large stone statue heads located on Easter Island

moat (n) – A deep, wide ditch, usually filled with water, typically surrounding a fortified medieval town, fortress, or castle as a protection against assault

MOB (n) – Acronym for "Man overboard"

mollusk (n) – A soft-bodied invertebrate, usually with a hard shell (e.g., snails, clams, squids and conch)

molten (adj) – Melted or liquefied by heat

molting (n) – The process by which an animal sheds one shell so that another, larger one can grow in its place

momentum (n) – An impelling force or strength

mongoose (n) – A small, cat-like carnivore, noted for its ability to kill poisonous snakes and rodents

monitor lizard (n) – Any of a family of usually very large, flesh-eating lizards of Africa, South Asia, and Australia: so named from the notion that they warn of the presence of crocodiles

monocotyledon (n) – Any of various flowering plants, such as grasses, orchids, and lilies, having a single cotyledon (a leaf of the embryo of a seed plant) in the seed

monocrop (n) – A single crop planted in one area at one time

monoculture (n) – The cultivation of a single crop

monohull (n) – A boat that is comprised of a single hull

monolith (n) – Something sculpted of a single large block of stone

monopoly (n) – Exclusive control over a product or market

monotreme (n) – The lowest Order of mammal, comprising of primitive egg-laying mammals restricted to Australia and New Guinea and consisting of only the platypus and the echidna

moor (v) – To tie up a vessel using cables, lines, or an anchor

mooring line (n) – A line or rope used to tie up a vessel

moped (n) – A bicycle propelled by a small motor

morphology (n) – The study of structure or systems, such as muscles of bones

morphotic (adj) – The manner in which an organism or any of its parts develops

mortality (n) – Death rate; the number of deaths in a given time or place

mortality rate (n) – The rate at which a particular organism population dies

mortar (n) – Any of various bonding materials, especially a mixture of cement or lime, sand and water, that hardens in place and is used to bind together bricks, stones or other building materials

mosque (n) – A building used for public worship by Muslims

"mother blocking" (n) – A whale behavior in which, if approached by a boat, a mother whale will position herself between the boat and her calf

mother watch (n) – An all-day watch that is responsible for cooking for the entire crew and cleaning the boat

motif (n) – A theme or central idea

motile (adj) – Moving or having the power to move spontaneously

motorsail (v) – In nautical terms, to travel forward with the aid of both a ship’s sails and its motor

motorway (n) – A British term for highway

Mount Olympus (n) – The highest point in Greece; early Greek mythology designated its summit as the home of the gods

mozzie (n) – Australian word for mosquito

mud flat (n) – A low, muddy area of land that is flooded at high tide and uncovered at low tide

muesli (n) – A mixture of usually untoasted rolled oats and dried fruit, often used as a breakfast cereal

muchacha (n) – The Spanish word for girl

mulatto (n) – A person of both African and Caucasian ancestry, usually possessing light brown skin

mulch (n) – Leaves, straw, etc. that is spread on the ground around a plant to inhibit weed growth and to lessen the evaporation of water from the soil

mulch (v) – To place leaves, straw, etc. on the ground around a plant to inhibit weed growth and to lessen the evaporation of water from the soil

mule (n) – In the Panama Canal, a powerful machine that uses lines to help steady a ship in the locks

multihull (n) – A boat that is comprised of two or more hulls, as in a catamaran (2 hulls) or trimaran (3 hulls)

multivariate (adj) – Involving more than one variable

mundane (adj) – Ordinary

municipal (adj) – Having to do with a city or town, or the government of the same

municipality (n) – A city or town that has its own government

munitions (n) – War supplies, especially weapons and ammunition

murky (adj) – Darkened or clouded with sediment

muster (n) – A gathering together or assembling

muster (v) – To assemble or gather together

mutineer (n) – One who rebels against those in charge, e.g., a sailor against ship officers

mutuation (n) – Random change in heredity material (genes; DNA)

myriad (n) – A vast number

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