subsidiarya.[L. subsidiarius: cf. F. subsidiaire. See Subsidy.]1. Furnishing aid; assisting; auxiliary; helping; tributary; especially, aiding in an inferior position or capacity; as, a subsidiary stream.()Chief ruler and principal head everywhere, not suffragant and subsidiary. (Florio.)They constituted a useful subsidiary testimony of another state of existence. (Coleridge.)2. Of or pertaining to a subsidy; constituting a subsidy; being a part of, or of the nature of, a subsidy; as, subsidiary payments to an ally.()George the Second relied on his subsidiary treaties. (Ld. Mahon.)n. One who, or that which, contributes aid or additional supplies; an assistant; an auxiliary.(Hammond.)