Definify.com

Webster 1913 Edition

Noun.

A bastard; colloquially, a low, scurvy fellow; – used generally in contempt, or in coarse humor. Also used adjectively.

[Archaic]

Shak.

Noun.

A bastard; a word used generally in contempt.

whoreson ‎(plural whoresons)

An illegitimate child born of unwed parents.
1605, Though this knave came something saucily to the world before he was sent for, yet was his mother fair, there was good sport at his making, and the whoreson must be acknowledged. — William Shakespeare, King Lear I.i
(literally) The son of a prostitute.

illegitimate child