Etymology Dictionary

WAG,  to move from side to side, shake to and fro.  (Scand.)   M. E. waggen, introduced (probably) as a Northern word in Chaucer, C. T. 4037; but also in P. Plowman, B. viii. 31, xvi. 41.   Earlier, in Havelok, 89.—O. Swed. wagga, to wag, fluctuate; whence wagga, a cradle, wagga, to rock a cradle (Ihre); Swed. vagga, a cradle, or as verb, to rock a cradle.   Cf. Icel. vagga, a cradle; Dan. vugge, a cradle, also, to rock a cradle.   Closely allied to A. S. wagian, to move, vacillate, rock (Grein, ii. 637), which became M. E. wawen, and could not have given the mod. form wag.   In Wyclif, Luke, vii. 25, the later version has 'waggid with the wynd,' where the earlier version has wawid.   β. The A. S. wagian is a secondary weak verb, from the strong verb wegan (pt. t. wæg, pp. wagen), to bear, move, carry (weigh), Grein, ii. 655; and similarly the O. Swed. wagga is from the Teut. base WAG (Aryan ✔WAGH), to carry; see Weigh, Waggon.   Der. wag, sb., a droll fellow, L. L. L. v. 2. 108, as to which Wedgwood plausibly suggests that it is an abbreviation for wag-halter, once a common term for a rogue or gallows-bird, one who is likely to wag in a halter; see Nares; and cf. 'little young wags...these are lackies;' Holinshed, Descr. of Ireland, ed. 1808, p. 68.   Hence wagg-ish, wagg-ish-ly, wagg-er-y (formed like knav-er-y).   Also wagg-le, q.v.; wag-tail, q.v.; wag-moire, a quagmire, Spenser, Shep. Kal. Sept. 130.   And see wedge, wing.