Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† tēnesmos, i, m., = τεινεσμός, a straining at stool, tenesmus, Plin. 28, 14, 59, § 211; 20, 6, 23, § 54; 20, 21, 84, § 227; Nep. Att. 21, 2; Scrib. Comp. 142 (in Cels. 4, 18, written as Greek).