consultant n.

"ask advice of, seek the opinion of as a guide to one's own judgment," 1520s, from French consulter (16c.), from Latin consultare "consult, take the advice of," frequentative of consulere "to take counsel, meet and consider," originally probably "to call together," as in consulere senatum "to gather the senate" (to ask for advice), from Proto-Italic *kom-sel-e-, from *kom- "with, together" (see con-) + *sel-e- "take, gather together," from PIE root *s(e)lh- "to take" (said to be also the source of Middle Welsh dyrllid "to earn," Gothic saljan "to sacrifice," Old Norse selja "to sell, hand over"). Related: Consulted; consulting.

agent or instrumental suffix, from Old French and French -ant, from Latin -antem, accusative of -ans, present-participle suffix of many Latin verbs. Compare -ance.