alacrity (n.) Look up alacrity at Dictionary.com
"liveliness, briskness," mid-15c., from Latin alacritatem (nominative alacritas) "liveliness, ardor, eagerness," from alacer (genitive alacris) "cheerful, brisk, lively;" a word of uncertain origin, perhaps cognate with Gothic aljan "zeal," Old English ellen "courage, zeal, strength," Old High German ellian.