Antonyms for the word "up-tight" are relaxed, easy-going, laid-back, chilled, carefree, calm, and cool. When a person is relaxed, they are not stressed or anxious. An easy-going individual is characterized by a calm and composed demeanor, which makes them approachable and friendly to be around. A laid-back person is one who is casual and unconcerned, thereby avoiding stressful situations out of their control. Someone who is chilled exudes a calm attitude that puts others at ease. A carefree person is free of worries and enjoys life to the fullest. Meeting a calm individual ensures that one can converse without pressure, whereas someone cool maintains composure and poise regardless of the situation.