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 worduttered inside at several hundred yards.
2. adjective [usually ADJECTIVE noun]
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.
directional in British English
(dɪˈrɛkʃənəl, daɪ-)
adjective
1.
of or relating to a spatial direction
2. electronics
a.
having or relating to an increased sensitivity to radio waves, sound waves, nuclear particles, etc, coming from a particular direction
b.
(of an aerial) transmitting or receiving radio waves more effectively in some directions than in others
3. physics, electronics
a.
concentrated in, following, or producing motion in a particular direction
b.
indicating direction
4.
indicating the direction something, such as a fashion trend, might take
directional fashion looks
Derived forms
directionality (diˌrectionˈality)
noun
directional in American English
(dəˈrɛkʃənəl; daɪˈrɛkʃənəl)
adjective
1.
of, aimed at, or indicating (a specific) direction
2.
designed for radiating or receiving radio signals most effectively in one or more particular directions
a directional antenna
3.
designed to pick up or send out sound most efficiently in one direction