spit (v.1) Look up spit at Dictionary.com
"expel saliva," Old English spittan (Anglian), spætan (West Saxon), transitive and intransitive, past tense *spytte, from Proto-Germanic *spitjan, from PIE *sp(y)eu-, of imitative origin (see spew (v.)). Not the usual Old English word for this; spætlan (see spittle) and spiwan are more common; all are from the same root. To spit as a gesture of contempt (especially at someone) is in Old English. Related: Spat; spitting.
spit (n.1) Look up spit at Dictionary.com
"saliva," early 14c., from spit (v.1). Meaning "the very likeness" in modern use is attested from 1825 (as in spitting image, attested from 1887); compare French craché in same sense. Spit-curl (1831) was originally considered colloquial or vulgar. Military phrase spit and polish first recorded 1895.
spit (n.2) Look up spit at Dictionary.com
"sharp-pointed rod for roasting meat," late Old English spitu "a spit," from Proto-Germanic *spituz (cognates: Middle Dutch and Dutch spit, Swedish spett (which perhaps is from Low German), Old High German spiz, German Spieß "roasting spit," German spitz "pointed"), from PIE *spei- "sharp point" (see spike (n.1)). This is also the source of the word meaning "sandy point" (1670s). Old French espois, Spanish espeto "spit" are Germanic loan-words. The verb meaning "to put on a spit" is recorded from c.1200.
spit (v.2) Look up spit at Dictionary.com
c.1200, "put on a spit, thrust with a spit," from late Old English sputtian "to spit" (for cooking), from spit (n.2). Meaning "pierce with a weapon, transfix, impale" is from early 15c. Related: Spitted; spitting. Nares' Glossary has spit-frog "a small sword."