A conditional word is a type of adverb or conjunction that expresses a condition or set of conditions. The four words UNLESS, MAY, ELSE, and MAYBE are all examples of conditional words. UNLESS is used to express a condition in which something will not happen UNLESS something ELSE happens first. MAY is used to express a possibility or permission. ELSE is used to express an alternative condition or consequence. Finally, MAYBE is used to express uncertainty or doubt.