What word best describes a person or action that is not strict?

The term that best describes a person or action that is not strict is "lenient." This word conveys the idea of being permissive or tolerant, often allowing for flexibility or forgiveness in rules, expectations, or conduct. For instance, a lenient teacher may allow students to submit assignments late without penalty, demonstrating a more flexible and understanding approach.

In contrast, the other options represent qualities that imply strictness or severity. "Rigid" suggests inflexibility and an unwillingness to change or adapt, which is the opposite of being lenient. "Harsh" refers to being overly severe or unkind, while "severe" denotes an extreme or strict adherence to rules or consequences. Therefore, "lenient" is the most appropriate choice to describe someone or something that is not strict.