Final answer:
A stabilizer muscle is one that contracts without significant movement to support the body or limb while other muscles perform their functions, such as the rotator cuff muscles during a bicep curl.
Step-by-step explanation:
A stabilizer muscle is a muscle that contracts with no significant movement to maintain a posture or fixate a joint. It supports the body or limb while the primary muscles perform a function. For example, during a bicep curl, the rotator cuff muscles serve as stabilizers for the shoulder joint while the biceps brachii acts as the prime mover to lift the weight. Stabilizer muscles often work to prevent unwanted movement and maintain alignment during an exercise.