Bound  

ZAM Network Wikibase™ Dictionary

Most items in a game world will be free to sell, trade or give away. Others will be Bound so they cannot be traded. There are a number of flavors of Binding commonly found in most MMOs.

• Bind on Pickup (BoP) or Soulbound - This is probably the most common and means that the item binds to the player that first receives it and cannot be traded. Some games proved a small window of time when the item can be traded but only to another player in the same group.
• Bind on Equip (BoE) - The item may be traded normally UNTIL a player actually uses it. Once they do the item becomes Bound and can only be sold to a merchant or destroyed.
• Account Bound or Bound to Account - The item cannot be traded to another player but can be given (usually via the mail) to another character on the same account. This allows "hand-me-down" gear. This is also common on items from special events, such as a cute costume hat.