By"-blow` (?), n.
1.
A side or incidental blow; an accidental blow.
With their by-blows they did split the very stones in pieces.
Bunyan.
2.
An illegitimate child; a bastard.
The Aga speedily . . . brought her [his disgraced slave] to court, together with her pretty by-blow, the present Padre Ottomano.
Evelyn.
© Webster 1913.