alacrity

Etymology

Coined between 1500 and 1510 from Latin alacritās, from alacer (“brisk”) + -itas (“-ity”).

noun

1. Eagerness; liveliness; enthusiasm.
   Besides, a wealthy man, well at ease, may pray to God quietly and merrily with alacrity and great quietness of mind, whereas he who lieth groaning in his grief cannot endure to pray nor can he hardly think upon anything but his pain. 1553 (posth.), Thomas More, A Dialogue of Comfort against Tribulation, Book I, Chapter 19
   "I'll get into the clothes this minute, if they're here," said Sam, with great alacrity. 1837, Charles Dickens, chapter 12, in The Pickwick Papers
   You have an overgrown alacrity For saying nothing much and hearing less […] 1920, Edward Arlington Robinson, “Tasker Norcross”, in The Three Taverns
   This evening, however, he was struck by the beaming alacrity of the aide-de-camp's greeting. 1922, Edith Wharton, chapter 24, in The Glimpses of the Moon
2. Promptness; speed.
   Yet this government never of itself furthered any enterprise, but by the alacrity with which it got out of its way. 1849, Henry David Thoreau, On the Duty of Civil Disobedience
   Not just that, but if the inlet of a turbopump impeller runs dry, it would overspeed with blinding alacrity. 2019, Tristan, Stack Exchange