interface has 2 distinct synonyms spread across 2 of its 4 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.
(chemistry) a surface forming a common boundary between two things (two objects or liquids or chemical phases)
(computer science) a program that controls a display for the user (usually on a computer monitor) and that allows the user to interact with the system
the overlap where two theories or phenomena affect each other or have links with each other
“the interface between chemistry and biology”
(computer science) computer circuit consisting of the hardware and associated circuitry that links one device with another (especially a computer and a hard disk drive or other peripherals)
Synonyms, antonyms and the broader and narrower relations for interface come from Princeton University’s WordNet. Full sources and licences.