What did Sartre mean by bad faith?

In the context of existentialism, Jean-Paul Sartre used the term bad faith (mauvaise foi) to describe a form of self-deception or dishonesty in which an individual denies their radical freedom and responsibility.12

Because Sartre believed that "existence precedes essence," humans are not defined by any predetermined purpose or nature. Consequently, individuals are entirely free to choose how they live. Bad faith occurs when a person attempts to escape this burden of choice by pretending they are not free—acting as if they are a "thing" (or "In-itself") determined by external forces, social roles, or past circumstances.32

By claiming that they are "compelled" by their situation or nature to act in a certain way, individuals in bad faith flee from the truth of their own self-determination. For Sartre, this denial is a fundamental failure to live "authentically," as it represents a vain attempt to avoid the dread and responsibility that necessarily accompany human freedom.132