(especially of soldiers) to…. muster in, to enlist into service in the armed forces. 2. The meaning of MUSTER is a representative specimen : sample. muster synonyms, muster pronunciation, muster translation, English dictionary definition of muster. To muster the resolve to change your thinking and claim your financial power, start by examining your beliefs about money. See ‘Meaning & use’ for definitions, usage, and quotation evidence. Define muster. Dictionary of Collective Nouns and Group Terms. He traveled around West Africa trying to muster support for his movement.