-shən ə l, -shnəl adjective
1. : relating to direction in space:
a. : moving, aiming, or leading in some particular direction
a strictly directional flight on a great circle
directional lines showing winds and ocean currents
b. : suitable or used for detecting the direction in which or from which signals are received
plot position by directional radio
flying on the beam of a directional radio range
c. : so designed that performance depends on direction or is restricted in direction : more effective in some directions than others
a polarized directional electromagnet controls the position and shape of the tail flame — J.K.Elderkin
the use of directional broadcasting techniques had made it possible to increase the number of radio stations — F.L.Mott
specifically : narrowly selective as to direction in the emission or reception of signals
a highly directional microphone picks up sounds coming from a single direction
that a Geiger-Müller tube cannot be made directional enough and still retain any measure of workable sensitivity — Surgical Forum
d. of sound : controlled for giving depth and realism in motion pictures by the use of several sound tracks recorded at different parts of the set or location
e. : indicating the direction in which something lies or the direction to take or about to be taken
a directional airway marker
directional arrows for facilitating movement of traffic
flashing directional signals for motorcars and trucks
2. : relating to direction (as of thought, effort, or culture):
a. : aimed or moving in the direction of one or another object, objective, or condition
the picture presented is frankly chaotic; it is hard to recognize in it any unifying pattern, any directional trends — V.G.Childe
the directional quality of cultural change
b. : constitutive of purpose or motivation
3.
a. : consisting of or imposing direction or guidance
the directional role that profits play under capitalism
b. : suitable or contributory to the direction of dramatic performance
good plays and even good directional ideas frequently take on a distressingly ragged aspect in performance — H.E.Clurman
c. of an oil-well drilling : made at an angle with the vertical