The Collaborative International Dictionary of English v.0.48:

Spank \Spank\, v. i.
   To move with a quick, lively step between a trot and gallop;
   to move quickly. --Thackeray.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Spank \Spank\ (sp[a^][ng]k), v. t. [imp. & p. p. Spanked
   (sp[a^][ng]kt); p. pr. & vb. n. Spanking.] [Of unknown
   origin; cf. LG. spakken, spenkern, to run and spring about
   quickly.]
   To strike, as the breech, with the open hand; to slap.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Spank \Spank\, n.
   A blow with the open hand; a slap.
   [1913 Webster]

WordNet (r) 3.0 (2006):

spank
    n 1: a slap with the flat of the hand
    v 1: give a spanking to; subject to a spanking [syn: spank,
         paddle, larrup]

Moby Thesaurus II by Grady Ward, 1.0:

92 Moby Thesaurus words for "spank":
   admonish, bang, baste, bastinado, batter, beat, belabor, belt,
   birch, blip, box, bring to book, buffet, bust, call to account,
   cane, castigate, chastise, chide, clout, club, correct, cowhide,
   cudgel, cuff, cut, drub, flagellate, flail, flap, flog, fustigate,
   give a whipping, give the stick, hammer, have words with,
   horsewhip, knock, knout, lace, lambaste, larrup, lash, lay on,
   lecture, maul, objurgate, paddle, paste, patter, pelt, pistol-whip,
   pommel, pound, pulverize, pummel, punch, punish, rap, rate,
   rawhide, rebuke, reprehend, reprimand, reprove, scold, scourge,
   set down, set straight, slap, sledgehammer, smack, smite, sock,
   straighten out, strap, stripe, swinge, switch, take down,
   take to task, thrash, thresh, thump, trounce, truncheon, upbraid,
   wallop, whack, whale, whip, whop