fillyyoudaoicibaDictYouDict
filly: see foal
filly (n.)youdaoicibaDictYouDict
c. 1400, filli, fyly, "a young mare, female colt or foal," possibly from Old Norse fylja, fem. of foli "foal" (see foal (n.)). Slang sense of "lively young girl" is from 1610s.