directional /dɪˈrɛkʃənəl, daɪ-/

• 1. 

  ADJ If something such as a radio antenna, microphone, or loudspeaker is directional, it works most effectively in one direction, rather than equally in all directions at once. (广播天线、麦克风或扬声器)定向型的 [技术]

  例：

  Unless he was equipped with a directional microphone, he was out of earshot.

  除非给他配备一个定向扬声器，否则谁也听不见他。

• 2. 

  ADJ Directional means relating to the direction in which something is pointing or going. 方向的 [技术] [usu ADJ n]

  例：

  Jets of compressed air gave the aircraft lateral and directional stability.

  压缩气体喷流从侧面和正面稳定了机身。