'narrow-muzzled' originates from English, formed by combining the adjective 'narrow' and the noun 'muzzle', where 'narrow' meant 'not wide' and 'muzzle' meant 'the projecting part of the face (nose and mouth) of an animal.'

'narrow' comes from Old English 'nearwe' meaning 'tight, narrow' (from Proto-Germanic *narwaz). 'muzzle' comes from Middle English 'musel', from Old French 'musel' (a diminutive related to words for snout). The compound adjective 'narrow-muzzled' developed in modern English usage as a descriptive term for animals.

The component words originally meant 'not wide' and 'snout/face'; combined they have retained the literal descriptive meaning 'having a narrow snout' in modern usage.