bridler

plural bridlers

1. Someone or something that bridles (puts a bridle on).
2. Someone or something that restrains and governs, like with a bridle.

   The Prelats which boaſt themſelves the only bridlers of Schiſm, God knows have been ſo cold and backward both there and with us to repreſs Hereſie and idolatry, that either through their careleſſneſs or their craft all this miſchief is befaln.

   1642, John Milton, The Reason of Church-Government Urg’d against Prelaty; republished in A Complete Collection of the Historical, Political, and Miscellaneous Works of John Milton, […], volume I, Amsterdam [actually London: s.n.], 1698, →OCLC, page 218

   Synonyms: restrainer, checker