Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
tortūra, ae, f. [torqueo] (post-class.). 
- I.  A twisting, wreathing: sarmenti, Pall. Febr. 9, 8.
 
- II.  Torment, torture: ventris, the gripes. colic.  =  tormina: tortura et extensio ventris dolorque, Veg. Vet. 1, 40 fin.; 2, 55.