Fromdis- +‎assent.

disassent (countable anduncountable,pluraldisassents)

1. Obsolete form ofdissent.
   • a.1548 (date written),Edward Hall,Richard Grafton, “(please specify the part of the work)”, inThe Vnion of the Two Noble and Illustre Famelies of Lancastre & Yorke, […], London:[…] Richardi Graftoni […], published1548,→OCLC:

     Whether he departed without the French kynges consent ordisassent, he[…]returned agayn to the Lady Margaret.

   • 1569,Richard Grafton, “Henry the Seuenth”, inA Chronicle at Large and Meere History of the Affayres of Englande […], volume II, London:[…]Henry Denham, […], forRicharde Tottle andHumffrey Toye,→OCLC,page898:

     But whether he departed without the French kings conſent ordiſaſſent, he deceiued in his expectacion, and in maner in diſpaire, retourned againe to the Lady Margaret his firſt fooliſh foundreſſe.

disassent (third-person singular simple presentdisassents,present participledisassenting,simple past and past participledisassented)

1. (obsolete) Todissent.

• “disassent”, inWebster’s Revised Unabridged Dictionary, Springfield, Mass.:G. & C. Merriam,1913,→OCLC.

• Daensists,staidness