The phrase "thick-skinned" is commonly used to describe a person who is not easily offended or affected by criticism. However, there are several other synonyms that can be used to convey a similar meaning, such as tough, resilient, unflappable, and impervious. These terms suggest a certain level of emotional toughness and resilience, indicating that a person is able to withstand negative feedback without becoming discouraged or upset. Other potential synonyms include stoic, insusceptible, unresponsive, and indifferent. Regardless of the specific word used, the implication is that the individual being described is able to remain calm and composed in the face of adversity, demonstrating a level of mental fortitude that is admirable and inspiring.