1. graded adjective & adjective If something such as a radio aerial, microphone, or loudspeaker is directional, it works most effectively in one direction, rather than equally in all directions at once. [technical] ⇒ Dish aerials are highly directional. ⇒ The directional microphone trained on Foresters Cottage could pick up every word uttered inside at several hundred yards. 2. adjective [usu ADJ n] Directional means relating to the direction in which something is pointing or going. [technical] ⇒ Jets of compressed air gave the aircraft lateral and directional stability.
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