a change in the form of a word (typically the ending) to express a grammatical function or attribute such as tense, mood, person, number, case, and gender

a set of word forms differing only in respect of inflections

the modulation of intonation or pitch in the voice

she spoke slowly and without inflection

the variety of his vocal inflections

a change of curvature from convex to concave at a particular point on a curve

the point of inflection of the bell-shaped curve