te·nes·mus 
(tə-nĕzməs)
(tə-nĕzməs)n.
A painfully urgent but ineffectual attempt to urinate or defecate.
[Medieval Latin tēnesmus, variant of Latin tēnesmos, from Greek teinesmos, from teinein, to strain, stretch; see ten- in the Appendix of Indo-European roots.]