light-o'-love

noun3

1. •
   Someone who is inconstant in love; a flirt.

   • You light-o'-love, a word or two. — 1626
2. •
   A promiscuous woman; a prostitute; a mistress or female lover.

   • Thus they fared, one after another, as the light-o'-love dame introduced them into her chamber, so that no one ventured to come near her. — 1828
3. •
   An old dance tune, whose name made it a proverbial expression of levity, especially in love matters.

   • Best sing it to the tune of light o' love. — 1590