INFLEXION, the action of bending inwards, or the condi tion of being bent or curved (from Lat. inflectere, to bend). In optics, the term "inflexion" was used by Newton for what is now known as "diffraction of light" (q.v.). For inflexion in geo metry see CURVE. Inflexion of the voice is a change in tone, pitch or expression. In grammar (q.v.) inflexion denotes the changes which a word undergoes to bring it into correct relations with the other words with which it is used. In English grammar nouns, pronouns, adjectives (in their degrees of comparison), verbs and adverbs are inflected.