Honorable means “worthy of honor,” “being honest”; honorary is applied to anything given as an honor only, such as an honorary degree (as distinguished from an earned one) or an honorary office that requires no duties; honorific means “showing respect” (and functional shift makes it a noun, meaning “any term or title bestowed out of respect”); an honorarium is a sum given in payment to a professional the value of whose work is not otherwise specified (its plurals are either honorariums or honoraria; see also SALARY); an honoree is someone being honored. All these terms are Standard. See FOREIGN PLURALS.
