Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
sūtūra, ae, f. [suo], a sewing together, a seam, suture: scutale crebris suturis duratum, Liv. 38, 29, 6; Cels. 7, 4, 3; 7, 4, 11 fin.; Petr. 13: calvariae, a suture of the skull, Cels. 8, 1 and 4.