Mac Dictionary’s definition:
1 a separate seat for one person, typically with a back and four legs.
• historical a sedan chair.
• short for chairlift .
2 the person in charge of a meeting or organization (used as a neutral alternative to chairman or chairwoman) : the deputy chair of the Supreme Soviet.
• an official position of authority, for example on a board of directors : the editorial chair.
• (also chair umpire) Tennis another term for umpire .
3 a professorship : he held a chair in physics.
4 a particular seat in an orchestra : [as adj., in combination ] she was fourth-chair trumpet.
5 ( the chair) short for electric chair .
6 chiefly Brit. a metal socket holding a railroad rail in place.
verb [ trans. ]
1 act as chairperson of or preside over (an organization, meeting, or public event).
2 Brit. carry (someone) aloft in a chair or in a sitting position to celebrate a victory.
take the chair act as chairperson.
ORIGIN Middle English : from Old French chaiere (modern chaire ‘bishop’s throne, etc.,’ chaise ‘chair’ ), from Latin cathedra ‘seat,’ from Greek kathedra. Compare with cathedral.
Without chairs, where would we sit down?