1. Usually, arms. weapons, esp. firearms.
2. arms, Heraldry. the escutcheon, with its divisions, charges, and tinctures, and the other components forming an achievement that symbolizes and is reserved for a person, family, or corporate body; armorial bearings; coat of arms.
?verb (used without object)
3. to enter into a state of hostility or of readiness for war.
--verb (used with object)
4. to equip with weapons: to arm the troops.
5. to activate (a fuze) so that it will explode the charge at the time desired.
6. to cover protectively.
7. to provide with whatever will add strength, force, or security; support; fortify: He was armed with statistics and facts.
8. to equip or prepare for any specific purpose or effective use: to arm a security system; to arm oneself with persuasive arguments.
9. to prepare for action; make fit; ready.
10. bear arms,
a. to carry weapons.
b. to serve as a member of the military or of contending forces: His religious convictions kept him from bearing arms, but he served as an ambulance driver with the Red Cross.
11. take up arms, to prepare for war; go to war: to take up arms against the enemy.
12. under arms, ready for battle; trained and equipped: The number of men under arms is no longer the decisive factor in warfare.
13. up in arms, ready to take action; indignant; outraged: There is no need to get up in arms over such a trifle.--Dictionary.com