tithe (n.) Look up tithe at Dictionary.com
a tenth part (originally of produce) due as support of the clergy, c.1200, from Old English teogoþa (Anglian), teoþa (West Saxon) "tenth," from Proto-Germanic *teguntha, from PIE *dekmto-, from *dekm "ten" (see ten). Retained in ecclesiastical sense while the form was replaced in ordinal use by tenth.
tithe (v.) Look up tithe at Dictionary.com
Old English teoþian "to pay one-tenth," from the root of tithe (n.). As "to impose a payment of a tenth," late 14c. Related: Tithed; tithing.