Contraction of smooth muscle in the walls of the bronchi and bronchioles, causing narrowing of the lumen. Compare: bronchoconstriction. /bron·cho·spasm/ (brong´ko-spazm) bronchial spasm; spasmodic contraction of the smooth muscle of the bronchi, as in asthma.pasm. 1. a sudden involuntary contraction of a muscle or group of muscles. 2. a sudden, transitory constriction of a passage, canal, or orifice; spasms usually occur when the nerves supplying muscles are irritated, and are often accompanied by pain.