Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† spasmus, i, m., = σπασμός, a cramp, convulsion, spasm (post-Aug. for convulsio), Plin. 22, 8, 9, § 21; 24, 7, 24, § 40; 30, 12, 36, § 110; Scrib. Comp. 171; Cael. Aur. Acut. 2, 3, 18.
Collat. form spasma, ătis, n., = σπάσμα, Plin. 28, 17, 72, § 237.