spit (v.) Look up spit at Dictionary.com
"expel saliva," Old English spittan (Anglian), spætan (West Saxon), from PIE *sp(y)eu-, of imitative origin (see spew). Not the usual Old English word for this; spætlan (see spittle) and spiwan (see spew) are more common. Meaning "to eject saliva (at someone or something) as a gesture of contempt" is in Old English.
spit (n.1) Look up spit at Dictionary.com
"saliva," c.1300, from spit (v.). Meaning "the very likeness" is attested from c.1600 (e.g. spitting image, attested from 1901); cf. French craché in same sense. Military phrase spit and polish first recorded 1895.
spit (n.2) Look up spit at Dictionary.com
"sharp-pointed rod on which meat is roasted," Old English spitu, from Proto-Germanic *spituz (cf. Middle Dutch spit, Swedish spett, Old High German spiz, German Spieß "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.