settle has 27 distinct synonyms spread across 13 of its 23 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. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
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.
settle into a position, usually on a surface or ground
“dust settled on the roofs”
settle conclusively; come to terms
“We finally settled the argument”
come to terms
“After some discussion we finally made up”
become settled or established and stable in one's residence or life style
“He finally settled down”
become resolved, fixed, established, or quiet
“The roar settled to a thunder”
establish or develop as a residence
“He settled the farm 200 years ago”
arrange or fix in the desired order
“She settled the teacart”
accept despite lack of complete satisfaction
“We settled for a lower price”
end a legal dispute by arriving at a settlement
“The two parties finally settled”
become clear by the sinking of particles
“the liquid gradually settled”
cause to become clear by forming a sediment (of liquids)
form a community
“The Swedes settled in Minnesota”
Synonyms, antonyms and the broader and narrower relations for settle come from Princeton University’s WordNet. Full sources and licences.