Weak/wiːk/ Definition 1 of 5Pro Tip 1/2Physical Condition Used to describe someone's low energy or strength, often due to illness or exertion. After climbing the stairs, she was feeling weak and had to rest. Pro Tip 2/2Avoid Overstatement Describing someone as 'weak' could be seen as offensive if not true or exaggerated. Calling the recovering patient weak may seem inconsiderate.