The phrase "keeping arm length" implies keeping a distance or separation from someone or something. Antonyms for this phrase would include being close, intimate, or connected. Other antonyms might include welcoming, accepting, or inviting. It's important to recognize that different contexts may require different antonyms, as "keeping arm length" may refer to physical distance, emotional distance, or even a business or legal separation. For instance, antonyms for "keeping arm length" in a legal context might include merging, partnering, or uniting. Regardless of the context, antonyms for "keeping arm length" suggest a connection or closeness that is absent when we keep distance.