Definition of "familiar"

The story struck the depressingly familiar note with which true stories ring in the tried ears of experienced policemen. No one queried it. It was in the classic pattern of human weakness, mean and embarrassing and sad.

1963, Margery Allingham, “Eye Witness”, in The China Governess: A Mystery, London: Chatto & Windus, page 249

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 July 20, “Welcome to the plastisphere”, in The Economist, volume 408, number 8845

Be thou familiar; but by no meanes vulgar: […]

c. 1599–1602 (date written), William Shakespeare, “The Tragedie of Hamlet, Prince of Denmarke”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act I, scene iii], page 156, column 1

familiar feuds

1822, Lord Byron, Werner

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

[A] friend of mine, that finding a Receipt in Braſsivola, would needs take Hellebor in ſubſtance, & try it on his own perſon; but had not ſome of his familiars come to viſite him by chance, he had by his indiſcretion hazarded himſelfe; many ſuch I have obſerued.

1624, Democritus Junior [pseudonym; Robert Burton], “Concerning the Patient”, in The Anatomy of Melancholy: […], 2nd edition, Oxford, Oxfordshire: Printed by John Lichfield and James Short, for Henry Cripps, partition 2, section 1, member 4, subsection 3, page 199