clearance (n.)

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

  2. vertical space available to allow easy passage under something

    [ Syn: headroom , headway ]

  3. permission to proceed; the plane was given clearance to land'

The dictionary is based on the WordNet Electronic Lexical Database.
WordNet 3.0 Copyright 2011 by Princeton University. All rights reserved.