subsonic /sʌbˈsɒnɪk/

• 1. 

  ADJ Subsonic speeds or aeroplanes are very fast but slower than the speed of sound. 次音速的 [ADJ n]

  例：

  This is 20,000 feet higher than most subsonic airliners.

  这比多数的次音速客机要高上两万英尺。