Teeter is an alteration of dialectal titter ('to seesaw, totter'), from Middle English titeren, of Scandinavian origin (compare Old Norse titra 'to shake, shiver'). The historical chain includes Old Norse titra. The quoted older senses, "to seesaw, totter" and "to shake, shiver", supply the semantic anchors for teeter. The formation is best read as borrowed: the word teeter carries its older form-history into a compact English lexical shape. In present English it is used as a verb, "to move or balance unsteadily; to waver". English derivatives include teetering and teetered; related English forms include totter and teeter-totter. The result is a verb and noun whose etymology preserves both the older form and the later English specialization.