Is it ensure, insure, or assure?
1530s, in part a back-formation from constipation, in part from Latin constipatus, past participle of constipare (see constipation). Earlier as an adjective (early 15c.); an earlier verb in this sense was constipen (late 14c.). Related: Constipated; constipating.
constipate con·sti·pate (kŏn'stə-pāt')
v. con·sti·pat·ed, con·sti·pat·ing, con·sti·pates
To cause constipation in the bowels.