waste has 31 distinct synonyms spread across 14 of its 16 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is conserve.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
use inefficiently or inappropriately
“waste heat”
get rid of
“We waste the dirty water by channeling it into the sewer”
get rid of (someone who may be a threat) by killing
“The mafia liquidated the informer”
any materials unused and rejected as worthless or unwanted
“they collect the waste once a week”
Synonyms, antonyms and the broader and narrower relations for waste come from Princeton University’s WordNet. Full sources and licences.
useless or profitless activity; using or expending or consuming thoughtlessly or carelessly
“if the effort brings no compensating gain it is a waste”
the trait of wasting resources
“a life characterized by thriftlessness and waste”
an uninhabited wilderness that is worthless for cultivation
“the barrens of central Africa”
(law) reduction in the value of an estate caused by act or neglect