'Headway' definitions:

Definition of 'headway'

From: WordNet
noun
Vertical space available to allow easy passage under something [syn: headroom, headway, clearance]
noun
Forward movement; "the ship made little headway against the gale" [syn: headway, head]

Definition of 'Headway'

From: GCIDE
  • Headway \Head"way`\ (-w[^u]rk`), n.
  • 1. The progress made by a ship in motion; hence, progress or success of any kind. [1913 Webster]
  • 2. (Arch.) Clear space under an arch, girder, and the like, sufficient to allow of easy passing underneath; clearance; headroom. [1913 Webster]