köken: Somewhat uncertain. The masculine nominative singular form is derived by syncope from alacris which probably developed by dissimilation from pre-Latin *alaklis, with the ending ultimately going back to *-tlis, from *-tl-, a variant of the zero-grade of the agent suffix *-tḗr. Compare volucer and volucris. However, De Vaan regards the origin of the *-kris ending as uncertain. The *ala- portion is…