Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
dē-frĕmo, ui, 3, v. n., to ceaseraging or roaring, to abate (post-class.): cum primus ille impetus defremuisset, Plin. Ep. 9, 13, 4; Sid. Ep. 9, 9; 1, 5 fin.: sensim ira, id. ib. 4, 12.