conjecture

Whether Columbus brought syphilis to the New World—or to the Old World—has been the subject of conjecture for at least 500 years. —Carl Zimmer, Science, 11 May 2001

… their voices rose in a chorus of conjecture and alarm, repeating the selfsame remark: “What is she going to do? I mean, is Betty going to faint?” —Edna O'Brien, New Yorker, 1 Jan. 1990

The reason why the French with superior man-power and American resources were doing so poorly was not beyond all conjecture. —Barbara W. Tuchman, The March of Folly, 1984

Peculiar features of early maps, which may have been nothing but a draftsman's whimsy, have inspired pages of vain conjecture. —Samuel Eliot Morison, The European Discovery of America, 1971

The biography includes conjectures about the writer's earliest ambitions.

a conjecture about the extent of the injury

Most of the book is conjecture, not fact.

It is fashionable now to conjecture that the Big Bang was caused by a random quantum fluctuation in a vacuum devoid of space and time. —Martin Gardner, Skeptical Inquirer, November/December 1998

… their traces left for future archaeologists to rediscover and perhaps to wonder or conjecture over. —Jane Jacobs, Cities and the Wealth of Nations, 1984

I am anxious to conjecture beforehand what may be expected from the sowing turneps [sic] in jaded ground, how much from the acre, & how large they will be? —Thomas Jefferson, letter, 29 Dec. 1794

Despairing of assistance and protection from below (as they foolishly conjecture) they talk of capitulating and coming upon terms with the French and Indians … —George Washington, 24 Apr. 1776, in The Papers of George Washington, 1984

Some have conjectured that the distant planet could sustain life.

We only conjecture about his motives.