Strait-laced is used to describe someone who is uptight, rigid, and overly conventional. Some antonyms for strait-laced could be unconventional, free-spirited, easy-going, liberal, or relaxed. The opposite of someone who is strait-laced would be someone who does not conform to societal norms and is not afraid to break the rules. They tend to be more open-minded and accepting of others, and less concerned with following strict codes of behavior. In contrast to a person who is strait-laced and formal, someone who is relaxed and carefree may be described as bohemian, unbuttoned, or casual.