1. (Med.) Of or pertaining to spasm; consisting in spasm; occuring in, or characterized by, spasms; as, a spasmodic asthma. 2. Soon relaxed or exhausted; convulsive; intermittent; as, spasmodic zeal or industry. Spasmodic croup (Med.), an affection of childhood characterized by a stoppage of brathing developed suddenly and without fever, and produced by spasmodic contraction ...