fa·mil·iar / fəˈmilyər/ • adj. 1. well known from long or close association: a familiar voice. ∎ often encountered or experienced; common: the situation was all too familiar. ∎ (familiar with) having a good knowledge of: be sure that you are familiar with the controls.2. in close friendship; intimate: she hadn't realized they were on such familiar terms. ∎ informal to an inappropriate degree.• n. 1. (also familiar spirit) a demon supposedly attending and obeying a witch, often said to assume the form of an animal.2. (in the Roman Catholic Church) a person rendering certain services in a pope's or bishop's household.3. a close friend or associate.DERIVATIVES: fa·mil·iar·ly adv.