adjective

• Having agreed to marry a particular person (one's fiancé or fiancée) or each other.
• Busy or employed.
• Greatly interested.
• (Britain) (of a telephone) Already involved in a telephone call when a third party calls.
• (architecture, of a column) attached to a wall or sunk into it halfway
• (of gears or cogs) in contact and in operation
• (military) being attacked or attacking
• (medicine, of a foetus) Having the widest part of its presenting part, usually the head, enter the pelvic brim or inlet.
• Synonym of engagé (“passionately committed to a cause”)