To make illegitimate.
Not conforming to known principles, or established or accepted rules or standards.
Not in accordance with the law.
Not sanctioned by marriage.
Not correctly deduced.
an illegitimate inference
Not authorized by good usage; not genuine.
an illegitimate word
Involving the fertilization of pistils by stamens not of their own length, in heterogonously dimorphic and trimorphic flowers.
illegitimate union; illegitimate fertilization