worst vs lowest

worst is a noun but lowest is not a noun.

Word	Noun	Adjective	Verb	Adverb
worst	Yes	Yes	Yes	Yes
lowest	No	Yes	No	Yes

worst (noun)	lowest (noun)
the weakest effort or poorest achievement one is capable of
the greatest damage or wickedness of which one is capable
the least favorable outcome

worst (adjective)	lowest (adjective)
(superlative of `bad') most wanting in quality or value or condition	lowest in rank or importance

worst (verb)	lowest (verb)
defeat thoroughly

worst (adverb)	lowest (adverb)
to the highest degree of inferiority or badness	in the lowest position; nearest the ground