In medicine, cat- denotes processes like breakdown (catabolism), descent (cataracts), or opposition (cataplexy). It modifies roots to imply reduction, reversal, or thoroughness, as in catatonic states or catadromous migrations.
latin & greek From Latinized Greek kata- (κατά), a preposition meaning “down from,” “against,” “back,” or “thoroughly,” from Proto-Indo-European *km̥t- (“down, with, along”).