consultation (n.)

early 15c., "a meeting of persons to consult together;" 1540s, "act of consulting," from Latin consultationem (nominative consultatio) "a mature deliberation, consideration," noun of action from past-participle stem of consultare "to consult, ask counsel of; reflect, consider maturely," frequentative of consulere "to deliberate, consider," originally probably "to call together," as in consulere senatum "to gather the senate" (to ask for advice), from assimilated form of com "with, together" (see con-) +  *selere "take, gather," for a total sense of "gather (the Senate) together," from PIE *selho- "to take, seize."

De Vaan writes: "Since consuleredoes not look like a derivative of consul (we would rather expect consulare), it appears that the verb was original and meant 'to get together, deliberate'."