1. Fundamental medium of time and space, postulated by most 19th Century scientists but largely abandoned as a concept after 1900. This was originally used in attempts to explain how waves can propagate through an apparent vacuum.

2. A name for a specific chemical, also known as Chloroform. It was given this name because it evaporates easily and evenly permeates air. In medicine, it was one of the first generally used anesthetics, but was abandoned because of its extreme flammability.

3. A state of matter at plasma or above. (Pond)