Definition of apsis:
- In a curve referred to polar coordinates, any point for which the radius vector is a maximum or minimum.
- One of the two points of an orbit, as of a planet or satellite, which are at the greatest and least distance from the central body, corresponding to the aphelion and perihelion of a planet, or to the apogee and perigee of the moon. The more distant is called the higher apsis; the other, the lower apsis; and the line joining them, the line of apsides.
- Same as Apse.
- "Account of a Tour in Normandy, Vol. II. (of 2)", Dawson Turner.
- "The English Language", Robert Gordon Latham.
- "Anecdotes of Painters, Engravers, Sculptors and Architects, and Curiosities of Art, (Vol. 2 of 3)", Shearjashub Spooner.