Armeries is a code/nickname used by Kpop community to shit talk about BTS without the fandom knowing. The directed fandom (Initially Army) found out about this nickname, and since they are crackheads they found it very funny and now use it on a daily basis. Armeries is now considered as the second name of the Army fandom. It is now added to the long list of codes/nicknames the fandom found such as: Botmys, Sushi stans (Can be used by Western Stan only!), Ratmys, Armchair, Armpits etc...
Used as a way to hate:
Someone: I hate Armeries! >:(
Someone: Armeries really think they're superior...
Used by the directed fandom:
An Army: ARMERIES! FAKE LOVE IS OUT NOW,STREAM THE MV !
An Army: YALL ARMERIES BETTER BUY LOVE YOURSELF: TEAR ON ITUNES
This is how they encourage each other.