bronchus (pl. bronchi) One of two branches into which the trachea or windpipe divides, with one branch leading to each of the lungs. The bronchus divides into smaller and smaller branches, called bronchioles, which extend throughout the lung, opening into the air sacs or alveoli. See also bronchitis

bronchus (bronchial tube) (pl. bronchi) One of the major air tubes in the lung. The trachea divides into two main bronchi, one for each lung, which split into smaller bronchi and then into bronchioles. The walls of the bronchi are stiffened by rings of cartilage.

bron·chus / ˈbrängkəs/ • n. (pl. -chi / -kī; -kē/ ) any of the major air passages of the lungs that diverge from the windpipe.

bronchus (bronk-ŭs) n. (pl. bronchi) any of the air passages beyond the trachea that has cartilage and mucous glands in its wall. See also bronchiole.
—bronchial adj.