1. the distance by which one thing clears another; the space between them

Definition categories: attribute, interval, separation

2. vertical space available to allow easy passage under something

Similar word(s): headroom, headway

Definition categories: quantity, room, way

3. permission to proceed

- the plane was given clearance to land

Definition categories: act, license, permission, permit

Sentences with clearance as a noun:

- 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