mode has 8 distinct synonyms spread across 5 of its 6 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.
a particular functioning condition or arrangement
“switched from keyboard to voice mode”
a classification of propositions on the basis of whether they claim necessity or possibility or impossibility
verb inflections that express how the action or state is conceived by the speaker
any of various fixed orders of the various diatonic notes within an octave
Synonyms, antonyms and the broader and narrower relations for mode come from Princeton University’s WordNet. Full sources and licences.