Meaning

noun a twist or aberration; especially a perverse or abnormal way of judging or acting

noun the amount by which a propagating wave is bent

noun the movement of the pointer or pen of a measuring instrument from its zero position

originFrom Latin dēflexiō, from dēflectere (“to deflect”; participle stem dēflex-) + -iō (suffix forming abstract nouns). The non-etymological spelling deflection is taken from the present stem dēflect-, associated with collection, dissection, etc. By surface analysis, deflect + -ion.

Etymology from Wiktionary, CC BY-SA 3.0