Inflection /(?)/

In·flec·tion

Inflection

n.
  1. The act of inflecting, or the state of being inflected.
  2. A bend; a fold; a curve; a turn; a twist.
  3. A slide, modulation, or accent of the voice; as, the rising and the falling inflection.
  4. The variation or change which words undergo to mark case, gender, number, comparison, tense, person, mood, voice, etc. (Gram.)
  5. Any change or modification in the pitch or tone of the voice. (Mus.)
  6. Same as Diffraction. (Opt.)

Phrases & Compounds
Point of inflection
the point on opposite sides of which a curve bends in contrary ways.