What does "spasmodic" mean?

Spasmodic: 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 of the vocal cords. It is sometimes fatal. Called also laryngismus stridulus, and childcrowing. -- Spasmodic stricture, a stricture caused by muscular spasm without structural change. See Organic stricture, under Organic.