Is it farther or further?
early 13c., "personally known;" past participle adjective from acquaint (v.). Of skills, situations, etc., from late 15c.
early 13c., from Old French acointier "make known, make acquaintance of," from Vulgar Latin accognitare "to make known," from Latin accognitus "acquainted with," past participle of accognoscere "know well," from ad- "to" (see ad-) + cognitus, past participle of cogniscere "come to know," from com- "with" (see com-) + gnoscere "know" (see notice). Originally reflective, "to make oneself known;" sense of "to gain for oneself personal knowledge of" is from early 14c. Related: Acquainted; acquainting.