command has 12 distinct synonyms spread across 6 of its 12 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.
an authoritative direction or instruction to do something
a military unit or region under the control of a single officer
the power or authority to command
“an admiral in command”
availability for use
“the materials at the command of the potters grew”
a position of highest authority
“the corporation has just undergone a change in command”
great skillfulness and knowledge of some subject or activity
“a good command of French”
(computer science) a line of code written as part of a computer program
Synonyms, antonyms and the broader and narrower relations for command come from Princeton University’s WordNet. Full sources and licences.