"to slope, overturn," c.1300, possibly from Scandinavian, or a special use of tip (n.). Intransitive sense of "fall over" is recorded from 1520s. Related: Tipped; tipping. Tipping point attested by 1972.
"end, point, top," early 13c., from Middle Low German or Middle Dutch tip "utmost point, extremity, tip" (cf. German zipfel, a diminutive formation); perhaps cognate with Old English tæppa "stopper" (see tap (n.)), from Proto-Germanic *tupp- "upper extremity." Tip-top is from 1702.
"give a small present of money to," c.1600, "to give, hand, pass," originally thieves' cant, perhaps from tip (v.3) "to tap." The meaning "give a gratuity to" is first attested 1706. The noun in this sense is from 1755; the meaning "piece of confidential information" is from 1845; the verb in this sense is from 1883; tipster first recorded 1862. For urban legendary origin as an acronym, see here.
noun
: our tip to him would be to behave (1845+)
verb
(also tip off) To give useful information or advice, esp advance information that gives an advantage of some sort: The room clerk tipped him/ Who tipped Larkin off? (1749+, variant 1891+)
[origin uncertain; perhaps fr the notion of tipping, that is, tilting something in someone's direction]