Resonance comes from Old French resonance, from Latin resonantia ('echo'), from resonare ('to resound'), from re- (intensive) + sonare ('to sound'), from sonus ('sound'). The historical chain includes Latin resonare, Latin sonus, and Proto-Indo-European *swen-. Older glosses in the chain include "echo", "to resound", "to sound", and "sound", which help explain the semantic range of the modern word. Morphologically, resonance is best read as compound and borrowing, yielding an English noun shaped by both form history and later usage. In current English it functions as a noun, with the sense "the quality of being deep, full, and reverberating; sympathetic vibration". related forms include resonant, resonate, resound, and sound. The result is an English noun whose etymology preserves the older forms while supporting the word's specialized modern meaning.