De*cid"u*ous (?; 135), a. [L. deciduus, fr. decdere to fall off; de- + cadere to fall. See Chance.] Biol.
Falling off, or subject to fall or be shed, at a certain season, or a certain stage or interval of growth, as leaves (except of evergreens) in autumn, or as parts of animals, such as hair, teeth, antlers, etc.; also, shedding leaves or parts at certain seasons, stages, or intervals; as, deciduous trees; the deciduous membrane.
© Webster 1913.