An acronym for "Out Of Stamina", meaning the Player character is low on health (very hurt or nearly dead) or sometimes low or out of energy, if a Rogue. Generally this should be a signal to other party members to pause so the character can regain some health or energy (sit down to have some Food, usually). Not as commonly used as OOM.
An acronym for "Out Of Speed". Used when a player finds himself out of Aspect of the Pack effect radius and threatens to fall further behind the rest of the party.