love-child

Noun

love child (plural love children)

1. (euphemistic) A child born as a result of a romantic liaison between parents not married to one another; an illegitimate child.
   • Two thousand a-year without debt or drawback — except for the little love-child, indeed; aye, I had forgot her; but she may be 'prenticed out at a small cost, and then what does it signify?1811, Jane Austen, chapter 30, in Sense and Sensibility

   Synonyms:

   bastard, bantling, bastardling, bastid, batchelor's son, by-blow, degenerate, fruit of adultery, haramzada, illegitimate

2. Something that includes influences of multiple predecessors.
   • The grunge genre was the love child of punk and metal.