'long-muzzled' originates from English, a compound of 'long' and 'muzzle'. 'long' originates from Old English 'lang' (from Proto-Germanic '*langaz'), where the root meant 'long'. 'muzzle' originates from Old French 'musel' (Middle English 'musele'), where 'musel' meant 'snout' or 'mouthpiece'.

'long' changed from Old English 'lang' to Middle English 'long' and eventually became the modern English 'long'. 'muzzle' changed from Old French 'musel' (and Middle English 'musele') and eventually became the modern English 'muzzle'. The compound formation produced 'long-muzzled' as a descriptive adjective in modern English.

Initially, the elements described 'long' and 'muzzle' separately (i.e., 'long snout'), and over time the compound 'long-muzzled' has retained the straightforward meaning 'having a long muzzle'.