adj., adv., n., & v.
--adj. most bad.
--adv. most badly.
--n. the worst part, event, circumstance, or possibility (the worst of the storm is over; prepare for the worst).
--v.tr. get the better of; defeat, outdo.
Phrases and idioms:
at its etc. worst in the worst state. at worst (or the worst) in the worst possible case. do your worst an expression of defiance. get (or have) the worst of it be defeated. if the worst comes to the worst if the worst happens.
Etymology: OE wierresta, wyrresta (adj.), wyrst, wyrrest (adv.), f. Gmc