means The specific moment at which a situation shifts decisively from one direction or state to another, marking the start of significant change.

from A plain English compound, joining "turn" (Old English "turnian"/"tyrnan," ultimately from Latin "tornare," to turn on a lathe) with "point" (from Latin "punctum," a pricked or pierced spot). It began as a literal navigational and mathematical idea — the place where a line or course changes direction, the point at which something turns — and the figurative sense of a decisive moment in events grew out of that spatial image.