familiar

Etymology

From Latin familiāris (“pertaining to servants; pertaining to the household”). Doublet of familial. Displaced native Old English hīwcūþ.

adj

1. Known to one, or generally known; commonplace.
   Plastics are energy-rich substances, which is why many of them burn so readily. Any organism that could unlock and use that energy would do well in the Anthropocene. Terrestrial bacteria and fungi which can manage this trick are already familiar to experts in the field. 2013-07-20, “Welcome to the plastisphere”, in The Economist, volume 408, number 8845
   There’s a familiar face; that tune sounds familiar.
2. Acquainted.
   I'm quite familiar with this system; she's not familiar with manual gears.
3. Intimate or friendly.
   We are on familiar terms now; our neighbour is not familiar
   Don’t be familiar with me, boy!
4. Of or pertaining to a family; familial.
   1822, Lord Byron, Werner familiar feuds

noun

1. (witchcraft) An attendant spirit, often in animal or demon form.
   The witch’s familiar was a black cat.
   The familiars of the magicians, on the other hand, were not in all cases evil, and often may have approximated the "guides" with whom present-day spiritualists are well acquainted. 1936, Rollo Ahmed, The Black Art, London: Long, page 75
   "What power hath gold?" Catweazle wondered as he picked up his familiar and put him in his special pocket. 1971, Richard Carpenter, Catweazle and the Magic Zodiac, Harmondsworth: Puffin Books, page 8
2. (obsolete) A member of one's family or household.
3. A member of a pope's or bishop's household.
4. (obsolete) A close friend.
5. (historical) The officer of the Inquisition who arrested suspected people.