Loose/luːs/ Definition 1 of 5Pro Tip 1/3Physical Security Describes something that might fall off or move if not secured better. Make sure the wheels on your skateboard aren't loose. Pro Tip 2/3Fixing Required Suggests an object needs repair to prevent problems. Check your bike before riding to ensure nothing is loose. Pro Tip 3/3Sensation Warning Relates to a feeling that parts of an object are moving unexpectedly. The loose railing on the stairs made me nervous.