The word 'tolerability' is a modern English formation built upon the classical Latin foundation of endurance. Its core, 'toler-', originates from the Latin verb tolerare, meaning to bear or endure, a concept with deep roots in human experience. This root was combined in Late Latin with the abstract noun-forming suffix '-abilitas', which denotes a capacity or quality. Thus, the literal construction "capacity for enduring" evolved into the contemporary, specialized abstract noun used primarily in medical and technical contexts to describe the acceptable level of adverse effects.

Structure: toler (endure) + ability (capacity) - toler: From Latin tolerare (to bear, endure). Its functional role is the core semantic root. - ability: From Latin -abilitas, a suffix forming nouns indicating a capacity or fitness. Its functional role is a noun-forming suffix.