What is tight lipped smile?

A tight-lipped smile is a facial expression where a person smiles, but their lips are pressed tightly together with little or no teeth showing. This type of smile is often associated with hiding one's true feelings or being hesitant to speak. It can also indicate discomfort, disapproval, or displeasure. The tight-lipped smile can be used to conceal emotions or mask discomfort or pain. It is often a nonverbal way for a person to communicate that they are not pleased or satisfied with a situation or conversation.