familiar

Concise Oxford English Dictionary © 2008 Oxford University Press:
familiar/fəˈmɪliə(r)/

▶adjective

• 1 well known from long or close association.

  ■ common; usual.

• 2 (familiar with) having a good knowledge of.

• 3 in close friendship.

  ■ inappropriately intimate or informal.

▶noun

• 1 (also familiar spirit) a demon supposedly attending and obeying a witch.

• 2 a close friend or associate.

• 3 (in the Roman Catholic Church) a person rendering certain services in a pope's or bishop's household.

– derivatives
familiarity noun (pl. familiarities),
familiarly adverb.

– origin ME: from OFr. familier, from L. familiaris, from familia ‘household servants, family’.