Bellum et arma

Arma sits at rank 134 and bellum at 180. No language puts war that high by accident: it is there because the texts that survived are histories, and histories are about fighting.

bellum and pugna, which are not the same size

Bellum is the condition. It starts, it is waged for years, it ends with a treaty. Pugna is one event inside it: the fight, on a day, in a place. A commander can lose the pugna and win the bellum, and Latin historians make that point constantly.

The verb you will meet with bellum is gerere, to carry: bellum gerere is to wage war. Weapons get capere or ferre: arma capere, take up arms.

bellum gerere - to wage war

arma capere - to take up arms

in armis esse - to be under arms, in the field

Arma is plural only. There is no singular armum in use, and translating it as an arm is wrong twice over. Treat the word as weaponry and it behaves. Exercitus is fourth declension, so its genitive is exercitus as well, and it comes from exerceo, to keep busy or train: an army is literally the drilled thing.

hostis is not your enemy personally

Hostis is the enemy of the state, the other side in a war. Latin had a separate word for the one you dislike, inimicus, built transparently from in- plus amicus. Calling a rival a hostis was an accusation, not an insult.

Older still, hostis meant stranger, which is why it shares a root with hospes, guest. English took both branches: hostile from the enemy sense, hospitality from the other.

Miles gives away the corpus in its own dictionary entry: soldier; knight. The second gloss is a thousand years of medieval Latin, in which miles is a man on a horse with a coat of arms.

Dux is built off duco, to lead, the same way rex is built off rego, to rule. It reaches English twice, once as the Italian duce and once as duke.

signum earns its rank in the army

Signum is a sign or mark generally, but in a battle narrative it is the standard, the unit's pole and emblem. That is why moving the standards is how Latin says an army moved.

signa ferre - to advance

signa inferre - to attack, to carry the standards against

The English family is huge and useful: sign, signal, design, resign, signature, ensign, and through the diminutive sigillum, seal.

virtus, regnum, lex, sanguis

These four are the abstractions the war words drag in with them.

• virtus is vir plus a suffix: what a man has. In a battle passage read it as courage and nothing else. Only later, in the philosophers and then the Christian writers, does it broaden into virtue - a drift English froze at the far end.
• regnum belongs to the reg- family with rex, regina, regio and regere. Kingdom, and also the power of a king: reign and regal both come out of it.
• lex, legis is a specific enacted statute. The wider idea of law-as-right is ius, and the English split preserves the difference exactly: legal, legislate, legitimate from one, justice, jurist, jury from the other. Privilegium, a law for one person, gives privilege.
• sanguis, sanguinis is blood, bloodshed, and lineage. Consanguinity is the third sense; sanguine is a medieval detour through the theory of humours.

The trap: bellum is not bellus

Bellum means war. Bellus means pretty, and gives belle, embellish and beau. They are unrelated, they differ by one letter, and neuter bellum looks exactly like the neuter of the adjective. Context settles it every time, but only if you know there is something to settle.

The stems

Military, ducal, legal, sanguine, exercise. The English word usually hands you the stem again, which is the hard half of the noun. Virtus is the exception on this list: virtue and virtuous both drop the -t- of virtut-, so that stem has to come from the genitive rather than from English.

Try it

Dux exercitum in bellum duxit. - The leader led the army into war.

Milites signum viderunt. - The soldiers saw the standard.

Hostis arma cepit. - The enemy took up arms.

Rex legem populo dedit. - The king gave the people a law.

Virtute, non sanguine, regnum stetit. - The kingdom stood by courage, not by blood.