wal•lopˈwɒl əp(v.; n.)-loped, -lop•ing

1. (v.t.)to beat soundly; thrash.

2. to strike with a vigorous blow; belt; sock:

   to wallop the ball out of the park.

   Category: Informal

3. to defeat thoroughly, as in a game.

   Category: Informal

4. (v.i.)to move clumsily.

   Category: Informal

5. (of a liquid) to boil violently.

6. Obs. to gallop.

7. (n.)a vigorous blow.

8. the ability to deliver vigorous blows, as in boxing.

9. Informal. the ability to make a forceful impression; punch: a pleasurable thrill; kick.

   an ad that packs a wallop.

   Category: Informal

Origin of wallop:

1300–50; ME walopen to gallop, wal(l)op gallop < AF waloper (v.), walop (n.), OF galoper, galop; see gallop

wal′lop•er(n.)