Agender describes a person with no gender identity. This means the person feels like neither a man nor a woman.[1] (The prefix "a-" means 'no' or 'none,' so "a-gender" means 'no gender'.) They might identify as a non-binary gender, or they might feel they belong to no gender at all.[2]
Agender people are sometimes called "genderless", "genderqueer", or "ungendered". Some agender people may also identify themselves as transgender. Others do not, because they feel "transgender" implies that they identify as a specific gender.