A shirtless person is someone who isn't wearing a shirt.
The word "shirtless" is often used to describe people who are feeling relaxed and casual. For example, you might see friends at the beach or park without their shirts on, enjoying the warm weather. In some cultures, going shirtless is common in public places like beaches or gyms. Even if you're not physically present with someone, you might hear someone say "He's so laid back, he was walking around shirtless all day" to describe their relaxed attitude.
(chiefly of a man) Not wearing a shirt; having a bare torso.
