Hemi cycle is a term that refers to a half-circle or a semicircle. However, there are a few synonyms for hemi cycle, which can be used in certain contexts. One synonym is a semidome, which refers to a half-dome shape used in architectural structures. Another synonym is a crescent, which describes a curved or arched shape that resembles a partial circular shape. A semi-ellipse is also a synonym for hemi cycle, which describes a symmetrical curve that has two focal points. Lastly, a semicircular arch is another synonym for hemi cycle and is commonly used in architecture to create a half-circle or arch shape.