Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
suf-frēnātĭo (subf-, also suffraen-), ōnis, f. [freno], a binding down fast, cementing: lapidis, Plin. 36, 22, 49, § 169: globus multā suffrenatione devinctus, Isid. Orig. 19, 10.