Synonyms for illegitimate

modified

1. Unlawful

   contraband, wrong, illicit, irregular; see illegal, wicked 1.

2. Born of unmarried parents

   born out of wedlock, natural, fatherless, bastard, misbegotten, unlawfully begotten, of illicit union, baseborn, unfathered, byblown, born on the wrong side of the sheet*.

3. Illogical

   twisted, unsound, incorrect, unacceptable; see illogical, wrong 2.