familiar has 7 distinct synonyms spread across 4 of its 7 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. Its 2 recorded opposites are unfamiliar, strange.
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.
well known or easily recognized
“a familiar figure”
within normal everyday experience; common and ordinary; not strange
“familiar ordinary objects found in every home”
(usually followed by `with') well informed about or knowing thoroughly
“conversant with business trends”
Synonyms, antonyms and the broader and narrower relations for familiar come from Princeton University’s WordNet. Full sources and licences.
a person attached to the household of a high official (as a pope or bishop) who renders service in return for support
a spirit (usually in animal form) that acts as an assistant to a witch or wizard