supposure

From suppose +‎ -ure.

supposure (plural supposures)

1. (obsolete) supposition; conjecture
   • 1662 (indicated as 1663), [Samuel Butler], “[The First Part of Hudibras]”, in Hudibras. The First and Second Parts. […], London: […] John Martyn and Henry Herringman, […], published 1678; republished in A[lfred] R[ayney] Waller, editor, Hudibras: Written in the Time of the Late Wars, Cambridge, Cambridgeshire: University Press, 1905, →OCLC:

     Thy other arguments are all Supposures, hypothetica

“supposure”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.