"Be mark" refers to a recognizable or distinguishable feature or characteristic of someone or something. Antonyms for this phrase could include words such as unremarkable, indistinct, unremarked, or unnotable. These words suggest something or someone that lacks clear standout qualities or features. An individual or object that is unremarkable might blend into the background, go unnoticed, or fail to capture attention or interest. Conversely, a person or thing that is marked by distinct or notable characteristics is likely to be memorable, easily recognizable, or possess qualities that set it apart from others.