alacrity

the word 'alacrity' entered english in the late 15th century, directly from the latin 'alacritas', which itself derives from the adjective 'alacer', meaning lively or brisk. the latin 'alacer' is of uncertain origin, though it may be related to a proto-indo-european root conveying swiftness or agility. the suffix '-ity', a common nominalizer from latin, transforms the adjectival quality into an abstract noun denoting the state of being. thus, the literal "state of being lively" evolved into the modern abstract sense of prompt and eager willingness.

Structure: alacr (lively) + ity (noun suffix) alacr (from latin 'alacer', meaning brisk, lively, eager); ity (from latin '-itas', a suffix forming nouns indicating a state or condition).