force has 23 distinct synonyms spread across 14 of its 18 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.
(physics) the influence that produces a change in a physical quantity
“force equals mass times acceleration”
group of people willing to obey orders
“a public force is necessary to give security to the rights of citizens”
a unit that is part of some military service
“he sent Caesar a force of six thousand men”
an act of aggression (as one against a person who resists)
“he may accomplish by craft in the long run what he cannot do by force and violence in the short one”
one possessing or exercising power or influence or authority
“the mysterious presence of an evil power”
a group of people having the power of effective action
“he joined forces with a band of adventurers”
a putout of a base runner who is required to run; the putout is accomplished by holding the ball while touching the base to which the runner must advance before the runner reaches that base
“the shortstop got the runner at second on a force”
to cause to do through pressure or necessity, by physical, moral or intellectual means
“She forced him to take a job in the city”
Synonyms, antonyms and the broader and narrower relations for force come from Princeton University’s WordNet. Full sources and licences.