Beat, pound, pummel, thrash, buffet, baste, belabor are comparable when they mean to strike repeatedly.
Beat, the usual and general word of this group, may imply no more than the simple action of repeated striking (as with one’s hands or an implement). The purpose is usually suggested by the object beaten, even when the manner of beating or the kind of implement used is not specifically stated.
Pound suggests beating with a weight or pestle to crush or reduce to a pulp or powder (as in grinding meal). More often the term implies heavier, more damaging blows than beat; it may suggest repeated striking (as by a heavy hammer, strong doubled fists, the hooves of horses, bombs, or shells), and it often also suggests rhythmical, loud, and heavy sounds.
Pummel implies the beating of a person with one’s fists: although it does not suggest as heavy blows as pound, it carries a stronger suggestion of continuous raining of blows and, often, of the infliction of injury than beat.
Thrash in its basic sense means to separate the grain (as of wheat) from the husks and straw, originally by beating or striking again and again (as with a flail).
Consequently thrash usually means to strike repeatedly in a manner suggestive of strokes with a flail and usually with an implement (as a stick or whip).
Buffet implies a repeated striking with or as if with an open hand: it therefore suggests a slapping rather than a pounding and in extended use is employed chiefly with reference to something which dashes against the face or the body in the manner of a slap or which one fights as if by slapping.
Belabor implies a prolonged and mighty basting or buffeting.