- I -

ice age (n) – A geologic time when large parts of the Earth were covered with glaciers

igneous (adj) – Formed by volcanic action or intense heat

iguana (n) – A large tropical lizard having a row of spines from neck to tail

illiteracy (n) – Inability to read or write

immersion suit (n) – A special bodysuit designed to protect a person from the cold and wet; used on ships in case of emergency

immigrant (n) – One who travels to a new country, region or environment in order to settle there

imminent (adj) – About to occur; impending

impassable (adj) – Impossible to pass, cross or overcome

impede (v) – To retard or obstruct the progress of; hinder

impediment (n) – A hindrance; an obstruction

impending (adj) – About to take place

impervious (adj) – Incapable of being penetrated

impetus (n) – An impelling force; an impulse; something that incites; a stimulus

implement (v) – To carry out, accomplish or fulfill

implementation (n) – The process by which a plan is put into action

import (n) – An item brought in (to a country, region, etc.) from the outside

import (v) – To bring an item in (to a country, region, etc.) from the outside

impromptu (adj) – Prompted by the occasion rather than being planned in advance

"in irons" (adj) – Headed into the wind

inbreed (v) – To breed by continual mating of individuals of the same or closely-related stocks

incentive (n) – Something that encourages or influences one’s actions

incisor (n) – A tooth adapted for cutting or gnawing, located at the front of the mouth along the apex of the dental arch

inclination (n) – A characteristic disposition to do, prefer, or favor one thing rather than another; a propensity

inclinometer (n) – An instrument that measures the angle of a ship relative to the horozontal

income (n) – The money or other gain received by a person for labor, services or investment

incubate (v) – To go through the process of incubation

incubation (n) – The period in which an embryo develops within an egg, before hatching

incurrent (adj) – Affording passage to an inflowing current

indentured (adj) – Bound by contract to work for another for a specified amount of time, either as an apprentice to a master or as an immigrant to service in a colony

indentured servitude (n) – The state of being bound into the service of another by contract for a specified term

indicator species (n) – A plant or animal that is found in a particular habitat and that is indicative of that habitat

indigenous (adj) – Native

indigo (n) – A plant used to create a deep violet-blue dye

indispensable (adj) – Essential

induction (n) – Introduction or initiation

industrialization (n) – The process of creating larger industries and increasing machine production of goods within an economy

inertia (n) – In physics, the tendency of matter to remain at rest if at rest, or, if moving, to keep moving in the same direction, unless affected by some outside force

infamous (adj) – Having an exceedingly bad reputation; notorious

infertile (adj) – Not fertile; not productive; barren

inflation (n) – A persistent increase in the level of consumer prices or a persistent decline in the purchasing power of money, caused by an increase in available currency and credit beyond the proportion of available goods and services

inflorescence (n) – A flower cluster; a characteristic arrangement of flowers on a stem

infrastructure (n) – The system of public works of a country, state, or region

inherent (adj) – Existing naturally in someone or something; innate or inborn

inhibition (n) – A mental state or process that restrains or suppresses certain actions, emotions, thoughts, etc.

initiate (v) – To admit into a membership through an event or ceremony

initiative (n) – The first step in or introduction of a new approach

inlet (n) – A recess, such as a bay or cove, along a coast; a stream or bay leading inland from the ocean; a narrow passage of water

INMARSAT (n) – Literally, INternational MARitime SATellite; the satellite communication system that ships at sea can use to communicate with other ships or with land-based locations

innovate (v) – To make changes in things that are already established

innovative (adj) – Having the tendency to innovate

input (n) – In agriculture, materials used to maintain soil health and quality and to keep pests and disease under control; organic inputs exclude the use of synthetic chemicals and hormones in crop production

insect (n) – A class of animal in which the body of an adult is divided into the head, thorax, and abdomen; has three pairs of legs on the thorax; and usually two pairs of wings

insecticide (n) – A chemical used to kill insects

insectivore (n) – An animal that eats insects

in-situ restoration (n) – A conservation method that focuses on restoring organisms’ populations on site, in their natural setting

intangible (adj) – Incapable of being perceived by the senses

integrity (n) – The quality or state of being unimpaired or in perfect condition

intelligent design (n) – The theory that intelligent causes are necessary to explain the complex structures of biology and that these causes are empirically detectable

interbreed (v) – Hybridize; to crossbreed

intercrop (v) – To cultivate land by planting different crops in alternating rows

interface (n) – A point or plane of intersection between two systems, groups, disciplines, etc.

intermediary (n) – A "go-between"; someone who helps two sides of an issue, organization, etc. communicate

International Date Line (n) – An imaginary line drawn north to south through the Pacific Ocean along the 180^th meridian; by international agreement, each calendar day begins at midnight at this line, so when it is Monday just west of the line, it is Sunday just east of it

intertidal zone (n) – The shore zone between the high and low tide marks; a coastal habitat which exists close to land, in relatively shallow water, and is affected by tides

intriguing (adj) – Fascinating

intrinsic (adj) – Of or relating to the essential nature of a thing; inherent

inundate (v) – Overflow; to overwhelm as if with a flood

invasive (adj) – Tending to spread and infringe on others

inventory (n) – A store of goods and/or an itemized list of such a store

inventory (v) – To itemize a list of one’s food or supplies

invertebrate (n) – An animal without a backbone

invincible (adj) – Incapable of being overcome or defeated; unconquerable

ionosphere (n) – The outer part of the Earth’s atmosphere, beginning at an altitude of about 34 miles and extending to the outermost edge of the atmosphere

irony (n) – A humorous or subtly sarcastic expression in which the meaning of the words is the opposite of their usual sense

iridescent (adj) – Producing a display of lustrous, rainbowlike colors; brilliant, lustrous, or colorful in effect or appearance

iroko (n) – A species of tree (Chlorophora excelsa) primarily found on the Ivory Coast and Cameroons and often used for boat building and marine work, furniture and cabinet work

ironic (adj) – A situation in which the outcome is contrary to what is expected

irreparably (adv) – Impossible to be repaired, rectified, or amended

irrigate (v) – To supply land with water via ditches, artificial channels or sprinklers

irrigation (n) – The process of supplying land with water via ditches, artificial channels or sprinklers

isometric (adj) – Equality of measure (e.g., an organism that grows isometrically is one that retains its relative shape even when it changes in size)

isthmus (n) – A narrow strip of land with water on each side connecting two larger bodies of land

Back to Top