What is the Latin word for heavy-armed?

The usual Latin words for “heavy-armed” are cataphractus, legiō. The right choice depends on the sense; see the distinctions below.

English → Latin

“heavy-armed” in Latin

cataphractuswearing armor, mailed legiōA legion.

Riddle & Arnold A Copious and Critical English–Latin Lexicon, 1864

heavy-armed

gravis armaturae. Heavy-armed cavalry, equites gravis armaturae (general term): equites ferrati or cataphracti (cuirassiers). Heavy-armed infantry, pedites gravis armaturae; gravius peditum agmen (on the march): legiones (the Roman legions, which were always heavy-armed; opposed to levis armaturae; ☞ Cic., Phil., 10, 6, 14).

Quick answer

What is the Latin word for heavy-armed?: The usual Latin words for “heavy-armed” are cataphractus, legiō. The right choice depends on the sense; see the distinctions below.

Entry from J. E. Riddle & T. K. Arnold, A Copious and Critical English–Latin Lexicon (rev. C. Anthon, New York: Harper, 1864), digitised by Fergus J. P. Walsh, CC BY-SA 4.0; Latin markup adapted by latindictionary.co.