As a followup to the earlier post of the evolution of the paper, here’s another piece of information: the word “conjecture”, in the sense currently used (and sometimes abused), doesn’t appear in the Annales de l’ENS before the 1950’s (searching for “conjectur*” in the whole text, and disregarding two early papers of Jacobi and Beltrami which are really discussions of how they were led to some result or other, and some chemistry/mineralogy papers).