'armored-tailed' is a recent English compound formed from the adjective 'armored' and the adjective-forming past participle of 'tail' ('tailed'). 'Armored' ultimately comes from Old French (from Latin 'armatura'), where 'arma' meant 'arms' or 'equipment', and 'tail' comes from an Old English/Old French lineage ultimately referring to the hind appendage.

'armored-tailed' developed by compounding the modern English adjective 'armored' (from Middle English 'armoured' < Old French/Latin) with 'tailed' (the adjectival form of 'tail', from Old English/Old French roots), creating a descriptive compound meaning literally 'having an armored tail'.

The components originally referred separately to 'protective armor' (armored) and the 'hind appendage' (tail); combined as 'armored-tailed', the phrase has the specific descriptive meaning 'having a tail covered in protective plates or armor'.