Dictionary:

belabor

  (bĭ-lā'bər)

1. To attack with blows; hit, beat, or whip. See synonyms at beat.
2. To assail verbally.
3. To discuss repeatedly or at length; harp on: Don't belabor the point.

verb

To hit heavily and repeatedly with violent blows: assail, assault, baste, batter, beat, buffet, drub, hammer, pound, pummel, smash, thrash, thresh. Informal lambaste. Slang clobber. Idioms: rain blows on. See attack/defend, strike/miss.

Definition: criticize
Antonyms: praise

v

Definition: over=elaborate
Antonyms: understate

The verb has 3 meanings:

Meaning #1: to work at or to absurd length
  Synonym: belabour

Meaning #2: attack verbally with harsh criticism
  Synonym: belabour

Meaning #3: beat soundly
  Synonym: belabour