Inherited from Middle English *begel (attested in the plural begles), of uncertain origin. Possibly from Middle French beegueule (“one who keeps their mouth open”), whence modern French bégueule (“a colloquial insult said to women of low status and accused of stupidity, who always have their mouths gaped or open; a prude”); from Old French beer, bayer (“to gape, gawk”) + Old French gueule (“gullet”). The modern French bigle (“beagle”) however is a borrowing from the English. Alternatively, a modification of Middle English bedel (“beadle”) in the sense of "constable, detective". The change of /t/, /d/ to /k/, /ɡ/ before /l/ is common; compare hurkle, variant of hurtlen (“to hurtle”), and in Modern English, huckleberry, turkle (“turtle”), and stickle.
1
A small short-legged smooth-coated scenthound, often tricolored and sometimes used for hunting hares. Its friendly disposition makes it suitable as a family pet.
2
A person who snoops on others; a detective.
[…]whereas burying a body in the wooded area beyond the backyard was the quickest way to make a Nassau County Police Department beagle look good.2002, Susan Isaacs, Long Time No See, page 243:
Inherited from Middle English *begel (attested in the plural begles), of uncertain origin. Possibly from Middle French beegueule (“one who keeps their mouth open”), whence modern French bégueule (“a colloquial insult said to women of low status and accused of stupidity, who always have their mouths gaped or open; a prude”); from Old French beer, bayer (“to gape, gawk”) + Old French gueule (“gullet”). The modern French bigle (“beagle”) however is a borrowing from the English. Alternatively, a modification of Middle English bedel (“beadle”) in the sense of "constable, detective". The change of /t/, /d/ to /k/, /ɡ/ before /l/ is common; compare hurkle, variant of hurtlen (“to hurtle”), and in Modern English, huckleberry, turkle (“turtle”), and stickle.
1
To hunt with beagles.
[…] reading men who beagled for fresh air and exercise, impecunious hunting men who beagled for economy[…]1933, Charles Pascoe Hawkes, Heydays: a salad of memories and impressions, page 20:
2
To search.
[…]Pope clapped his hand to his forehead and beagled like a maniac; he had clean forgotten Thorofare Gap.1997, Fletcher Pratt, A Short History of the Civil War: Ordeal by Fire, page 150: