clearance

1. The act of clearing or something (such as a space) cleared. (countable, uncountable)
2. The distance between two moving objects, especially between parts of a machine (countable, uncountable)
3. The height or width of a tunnel, bridge or other passage, or the distance between a vehicle and the walls or roof of such passage; a gap, headroom. (countable, uncountable) · Clearance on these freeway overpasses is limited, so big trucks must detour.
4. A permission for a vehicle to proceed, or for a person to travel. (countable, uncountable) · The plane got clearance from air traffic control, and we were off.· He got clearance to travel to America, even though he had previous links to terrorists.
5. A permission to have access to sensitive or secret documents or other information. (countable, uncountable)
6. A permission to use something, usually intellectual property, that is legally, but not otherwise, protected. (countable, uncountable)
7. A sale of merchandise, especially at significantly reduced prices, usually in order to make room for new merchandise or updated versions of the same merchandise; sometimes as a closeout. (countable, uncountable)
8. The settlement of transactions involving securities or means of payment such as checks by means of a clearing house. (countable, uncountable)

Plural clearances