Altophobia is the fear of heights. People who have this fear may avoid climbing ladders, being on roofs of buildings, driving over mountains or bridges, and sometimes stairwells and railings. The origin of the word alto is Greek (meaning high) and phobia is Greek (meaning fear). Altophobia is considered to be a specific phobia, which is discussed on the home page. Altophobia is also known as Acrophobia and related to Aeroacrophobia (fear of open high places).