the.com/inflection

means A change in direction, tone, or pitch — the point where something shifts from one state or course to another.

from From Latin inflectere, 'to bend in' — in- ('in, toward') plus flectere ('to bend'), the same root that gives us 'flex' and 'deflect.' The word entered English through grammar first, describing how words bend their endings to show tense or case, then spread to describing voice (the bending of pitch in speech) and eventually curves and trends — anywhere a straight line learns to bend.