illegitimately

UK: /ˌɪlɪˈdʒɪtɪmɪtlɪ/

WordReference Random House Learner's Dictionary of American English © 2025

il•le•git•i•mate /ˌɪlɪˈdʒɪtəmɪt/   adj. 

1. born of parents who are not married to each other:
   an illegitimate child.
2. not allowed by rules or custom;
   unlawful;
   illegal.

il•le•git•i•mate•ly, adv. See -leg-.

WordReference Random House Unabridged Dictionary of American English © 2025

il•le•git•i•mate  (adj., n. il′i jit′ə mit;v. il′i jit′ə māt′), adj., n., v., -mat•ed, -mat•ing. 
adj. 

1. born of parents who are not married to each other;
   born out of wedlock:
   an illegitimate child.
2. not legitimate;
   not sanctioned by law or custom.
3. unlawful;
   illegal:
   an illegitimate action.
4. irregular;
   not in good usage.
5. Philosophy [Logic.] not in accordance with the principles of valid inference.
6. Show Business [Obs.] (formerly, in London)
   • of or pertaining 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.

n. 

7. a person recognized or looked upon as illegitimate.

v.t. 

8. to declare illegitimate.

• il-² + legitimate 1530–40

il′le•git′i•mate•ly, adv. 
il′le•git′i•mate•ness, il′le•git′i•ma′tion, n. 
Synonyms

• 2, 3. . See illegal.