'ensign-carriers' is a compound of 'ensign' and 'carrier'. 'Ensign' originates from Old French, specifically the word 'enseigne', where 'enseigne' meant 'sign' or 'badge' (from Latin 'insignia' meaning 'marks, emblems'). 'Carrier' comes from Middle English 'carier' (from Old French), ultimately from Late Latin 'carricare' meaning 'to load into a cart' (from Latin 'carrus' meaning 'wagon').

'ensign' changed from Old French 'enseigne' to Middle English forms like 'ensigne' and later became the Modern English 'ensign'. 'Carrier' developed from Middle English 'carier' (an agent noun from verbs meaning 'to carry') into the Modern English 'carrier'. The compound 'ensign-carrier' or the phrase 'ensign carrier' arose by combining the noun for the flag ('ensign') with the agent noun ('carrier') to denote a person who carries the flag.

Initially, 'ensign' referred broadly to a sign, badge, or emblem and 'carry'/'carrier' related to transport (often by cart). Over time 'ensign' narrowed to mean a flag or banner identifying a military unit, and 'carrier' came to mean one who carries something; together the compound came to mean 'one who carries a flag'.