climacteric, climax, corner, landmark, milestone, turning point, watershed

break, capper, clincher, crusher, highlight, topperconversion, metamorphosis, transfiguration, transformation, turnabout, turnaroundboiling point, breaking point, clutch, conjuncture, crisis, crossroad(s), crunch, crunch time, Dunkirk, emergency, exigency, extremity, flash point, head, juncture, zero hour