a person attached to the household of a high official (as a pope or bishop) who renders service in return for support
"The new secretary was told that Mr. Gable, the familiar assigned to the Archbishop's residence, would be managing all his travel arrangements starting Monday."
a spirit (usually in animal form) that acts as an assistant to a witch or wizard
"The young witch summoned her familiar, a black cat with glowing green eyes, to help her brew the evening potion."
An attendant spirit, often in animal or demon form.
"After years of wandering through the dark forest, the hunter finally summoned his familiar to guide him home from the treacherous valley."
In plain English: A familiar is a supernatural creature that appears as a trusted animal companion to witches and wizards.
"That old face is so familiar to me that I feel like we used to be friends."
Usage: Use "familiar" only when referring to a supernatural spirit that attaches itself to a witch or wizard. Do not use this term for someone you know well, as that is the standard adjective meaning.
within normal everyday experience; common and ordinary; not strange
"familiar ordinary objects found in every home"
"a familiar everyday scene"
"a familiar excuse"
"a day like any other filled with familiar duties and experiences"
(usually followed by `with') well informed about or knowing thoroughly
"conversant with business trends"
"familiar with the complex machinery"
"he was familiar with those roads"
Known to one, or generally known; commonplace.
"The melody from his childhood seemed so familiar that he instantly recognized it as a song everyone in town knew by heart."
In plain English: Familiar means being well known to someone because you have seen or experienced it often before.
"The song sounded familiar, so I recognized the melody immediately."
Usage: Use "familiar" to describe something that is well-known, ordinary, or easily recognized by people in general. Avoid using it to mean "very close," as that sense belongs to the word "intimate."
The word "familiar" comes from Middle English and originally Latin, where it meant something pertaining to a household or its servants. It entered modern usage by displacing the older Old English term for someone known well.