RIVAL, one who competes with another, one who strives :o out-do or excel another or to gain an object or end before or in preference to another. The Latin rivalis, which was !n classical Latin used of a competitor in love, meant by derivation one who used the same brook or stream (rivus) as another, hence a neighbour; thus in the Digest, xliii. 20, i. 26, " si inter rivales, id est qui per eundem rivum aquam ducunt, sit contentio de aquae usu." The term naturally applied more particularly to those who lived on opposite sides of a stream which would be a frequent subject of dispute as to rights.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)