arm

Arms, of course, are the upper limbs of the body. It’s also a term for weapons, especially guns (firearms).

The word arm, as in the body part, is a very old word in English; it’s recorded in Old English and comes from Germanic roots. Arms as in “weapons,” comes from the Latin arma, “tools of war,” which passed into English from French in the 1200s.  

In the Middle Ages, arms referred to various weapons (e.g., bows and arrows, catapults) and equipment of war, including defensive shields and armor. Today, arms for weaponry can sound a little dated, except for expressions like arms race, first used in the 1920s for the competitive buildup of weapons between nations (then nuclear arms race) and later extended as a metaphor for any competition. 

Another common arms-related expression is to take (up) arms, “to prepare for a (literal or figurative) fight.” Shakespeare’s Hamlet used the phrase in the famous “To Be or Not To Be” soliloquy:

To be, or not to be, that is the question:
Whether ’tis nobler in the mind to suffer
The slings and arrows of outrageous fortune,|
Or to take arms against a sea of troubles,
And by opposing end them? To die, to sleep;
No more …

The opposite expression, and just as familiar, expression is to lay down arms, or “surrender” or “stop fighting.” This is also used in reference to actual or imaginary combat.

By the late 1600s, the word arms was narrowing to its current sense of firearms, such as pistols and rifles. These arms are at the center of the much debated language of the Second Amendment of the U.S. Constitution, ratified in 1791: “A well-regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.”

A coat of arms was originally a type of outerwear that medieval knights wore in battle. They bore heraldic symbols representing who they were and who they were fighting for. Families and organizations later adopted these emblems as crests.

To be up in arms, which dates back to the late 16th century, means “ready to fight” and later, “very upset.”

On its own, arms for “weapons” sounds more formal, showing up in more historical texts and legal contexts. Expect to hear arms, though, in the discussion of gun rights in the U.S. surrounding the Second Amendment.

Also expect to hear arms in its related verbal form, to arm, “equip with a weapon,” (e.g., if a cop yells “He’s armed and dangerous!”). Armed, here, usually means carrying a gun.

More examples of arms:

“March on, march on, since we are up in arms;
If not to fight with foreign enemies,
Yet to beat down these rebels here at home.”
—William Shakespeare, Richard III, 1592–93

“China joins Russia in signaling it will veto any US resolution to extend arms embargo on Iran & resist snapback.”
—@farnazfassihi, May 2020

This content is not meant to be a formal definition of this term. Rather, it is an informal summary that seeks to provide supplemental information and context important to know or keep in mind about the term’s history, meaning, and usage.