Nouns

(n)bastard, by-blow, love child, illegitimate child, illegitimate, whoresonthe illegitimate offspring of unmarried parents

Adjectives

(s)illegitimate, illicit, outlaw, outlawed, unlawfulcontrary to or forbidden by law“an illegitimate seizure of power”, “illicit trade”, “an outlaw strike”, “unlawful measures”
(a)illegitimateof marriages and offspring; not recognized as lawful