Definitions:
adopt or be in a position in which one's weight is supported by one's buttocks rather than one's feet and one's back is upright

be or remain in a particular position or state

(of a parliament, committee, court of law, etc.) be engaged in its business

take (an examination)

live in someone's house while they are away and look after their pet or pets

a period of sitting

the way in which an item of clothing fits someone