The term "up holster" refers to the act of placing a weapon, such as a gun, back into its holster. There are several synonyms for this term, including reholster, sheath, encase, put away, and secure. Reholster refers to placing the weapon back into its holster after being temporarily removed. Sheath refers to the protective covering for a blade or firearm. Encase refers to putting something inside of a case or container. Put away simply means to stow something in its designated place. Finally, secure refers to ensuring that something is firmly in place, typically with a locking mechanism. These synonyms can be used interchangeably depending on the context of the situation.