In Masonic terminology this is the technical name of that ceremony in which the candidate walks around the Lodge. The word 4 is derived from the Latin prefix cireum, meaning "around," and ainbulare, meaning "walk," whence our ambulate, ambulatory, etc.; a circumambulation is therefore a walking around. In ancient religions and mysteries the worshippers walked around an altar; imitating the movements of the sun; this became known as circumambulation, and is the origin of our own ceremony.
- Source: 100 Words in Masonry