All about love

love (n.)
O.E. lufu "love, affection, friendliness," from Proto-Germanic.
*lubo (cf. O.Fris. liaf, Ger. lieb, Goth. liufs "dear, beloved;" not found elsewhere as a noun, except O.H.G. luba, Ger. Liebe), from PIE
*leubh- "to care, desire, love" (cf. L. lubet, later libet "pleases;" Sanskrit. lubhyati "desires;" O.C.S. l'ubu "dear, beloved;" Lith. liaupse "song of praise"). Meaning "a beloved person" is from c.1225.
The sense "no score" (in tennis, etc.) is 1742, from the notion of "playing for love," i.e. "for nothing" (1678).
Love-letter is attested from c.1240; love-song from c.1310. To be in love with (someone) is from 1508.
Love child "child born out of wedlock," first attested 1805, from earlier love brat (17c.).
Lovesick is attested from 1530; lovelorn from 1634 (see lose). Phrase for love or money "for anything" is attested from 1590. To fall in love is attested from 1423.
The phrase "no love lost" (between two people) is ambiguous and was used 17c. in ref. to two who love each other well (c.1640) as well as two who have no love for each other (1622).

-Online Etymology Dictionary-
For an idea of what the abbreviations mean, check the list.