Pertaining to a family; domestic.Having, or springing from, intimate and friendly social relations; closely intimate: as, a familiar friend; familiar companionship; to be on familiar terms with one.Having a friendly aspect or manner; exhibiting the manner of an intimate friend; affable; not formal or distant; especially, using undue familiarity; intrusive; forward.Characterized by ease or absence of stiffness or pedantry; unconstrained.Having an intimate knowledge; well knowing; well acquainted; well versed (in a subject of study): as, he is familiar with the works of Horace.Well known from frequent observation, use, etc.; well understood.Synonyms Close, intimate, amicable, fraternal, near.n. A familiar friend; an intimate; a close companion; one long acquainted; one accustomed to another by free, unreserved converse.n. A familiar spirit; a demon or evil spirit supposed to attend at call. See familiar spirit, under I.n. In the Roman Catholic Church, a member of the household of the pope or of a bishop, supported at his expense, and rendering him domestic, though not menial service. The familiar must live in the diocese of his superior.n. An officer of the Tribunal of the Inquisition who arrested persons accused or suspected. See inquisition.