Arm-length is a commonly used term that refers to the distance that can be reached with one's arm. However, it is sometimes necessary to use synonyms to convey the same meaning. Some synonyms for arm-length include armspan, arm-reach, and arm's distance. Other related terms include reach, stretch, extension, and distance. These words describe a similar physical concept but may have slightly different connotations or nuances. When expressing the idea of arm-length, it is important to choose the most appropriate synonym based on the context and intended meaning.