n. 25B6; verb
they mustered 50,000 troops : ASSEMBLE, mobilize, rally, raise, summon, gather (together), mass, collect, convene, call up, call to arms, recruit, conscript; US draft; archaic levy.
reporters mustered outside her house : CONGREGATE, assemble, gather together, come together, collect together, convene, mass, rally; formal foregather.
she mustered her courage : SUMMON (UP), screw up, call up, rally.
25B6; noun the colonel called a muster : ROLL-CALL, assembly, rally, meeting, gathering, assemblage, congregation, convention; parade, review.
25A0; pass muster BE GOOD ENOUGH, come up to standard, come up to scratch, measure up, be acceptable/adequate, fill/fit the bill; informal make the grade, come/be up to snuff.