n a measure of a person's intelligence as indicated by an intelligence test; the ratio of a person's mental age to their chronological age (multiplied by 100)
n a militant organization of Irish nationalists who used terrorism and guerilla warfare in an effort to drive British forces from Northern Ireland and achieve a united independent Ireland
n a retirement plan that allows you to contribute a limited yearly sum toward your retirement; taxes on the interest earned in the account are deferred
n belligerence aroused by a real or supposed wrong (personified as one of the deadly sins)