Webster's Revised Unabridged Dictionary · 1913

Beagle

Beagle ({not transcribed}) , noun

[Old English begele; perh. of Celtic origin; compare Ir. & Gael. beag small, little, Welsh bach. French bigle is from English.]

1.
A small hound, or hunting dog, twelve to fifteen inches high, used in hunting hares and other small game. See Illustration in Appendix.
2.
Figuratively: A spy or detective; a constable.