- born of parents who are not married to each other; born out of wedlock: an illegitimate child.
- not legitimate; not sanctioned by law or custom.
- unlawful; illegal: an illegitimate action.
- irregular; not in good usage.
- Logic. not in accordance with the principles of valid inference.
- Obsolete. (formerly, in London)
- of or relating to stage plays in which musical numbers were inserted because of laws that gave only a few theaters the exclusive right to produce straight dramas.
- acting in or producing such productions.
- a person recognized or looked upon as illegitimate.
verb (used with object), il·le·git·i·mat·ed, il·le·git·i·mat·ing.
- to declare illegitimate.
- born of parents who were not married to each other at the time of birth; bastard
- forbidden by law; illegal; unlawful
- contrary to logic; incorrectly reasoned
- an illegitimate person; bastard
1530s, “born out of wedlock,” formed in English (and replacing earlier illegitime, c.1500), modeled on Latin illegitimus “not legitimate” (see il- + legitimate). Sense of “unauthorized, unwarranted” is from 1640s. Phrase illegitimi non carborundum, usually “translated” as “don’t let the bastards grind you down,” is fake Latin (by 1965, said to date from c.1939) (Carborundum was a brand of abrasives).