| ionium |
a naturally occurring radioactive isotope of the chemical element thorium. |
| ionization chamber |
a gas-filled vessel fitted with two electrodes in which the current between the electrodes is a function of the amount of ionization of the gas. |
| ionize |
to separate or change partly or completely into ions. [3 definitions] |
| ionosphere |
layers of the earth's atmosphere located above the stratosphere from about thirty to two hundred and fifty miles above the earth's surface, and composed of rarefied gases that have been ionized by radiation from the sun. |
| iota |
the name of the ninth letter of the Greek alphabet. [2 definitions] |
| IOU |
a signed paper acknowledging a debt and often bearing these letters, meaning "I owe you". |
| -ious |
full of; having the characteristics of; having. |
| Iowa |
a Midwestern U.S. state between Illinois and Nebraska. (abbr.: IA) [3 definitions] |
| IP |
in computing, an abbreviation for Internet protocol, one of the main Internet communications protocols, which specifies the format of transmitted data and routing information. |
| iPad |
trademark for a tablet computer developed and sold by Apple, Inc. |
| ipecac |
either of two tropical South American plants related to madder, coffee, and gardenia, whose roots are used medicinally. [2 definitions] |
| iPhone |
trademark for a type of mobile telephone that includes an internet browser, camera, and music player. |
| iPod |
trademark for a pocket-sized digital audio player with a large storage capacity, primarily used to collect and play back downloaded digital music files. |
| ipomoea |
a plant of the morning glory family that has heart-shaped leaves and bears showy flowers. [2 definitions] |
| ipsative |
using a person's own assessment of his or her qualities, knowledge, or skills rather than using testing measures that allow comparison of an individual with others or with a set standard. (Cf. normative.) |
| ipse dixit |
(Latin) he himself said it; an unproven or dogmatic assertion. |
| ipsilateral |
pertaining to, situated on, or affecting the same side of the body. |
| ipso facto |
(Latin) by that fact itself. |
| IQ |
abbreviation of "intelligence quotient," a representation of mental age as determined by intelligence tests. |
| Ir |
symbol of the chemical element iridium. |
| ir-1 |
in; into. [2 definitions] |