head·way /-ˌwe/
 前進,航行速度,進展
 Head·way n.
 1. The progress made by a ship in motion; hence, progress or success of any kind.
 2. Arch. Clear space under an arch, girder, and the like, sufficient to allow of easy passing underneath; clearance; headroom.
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 headway
      n 1: vertical space available to allow easy passage under
           something [syn: headroom, clearance]
      2: forward movement; "the ship made little headway against the
         gale" [syn: head]