Reiner is a lunarimpact crater on the Oceanus Procellarum, in the western part of the Moon. It has a nearly circular rim, but appears oval in shape due to foreshortening. The rim edge is well-defined and has not been eroded by impacts. In the midpoint of the irregular crater floor is a central peak. Outside the rim is a hummocky rampart that extends out across the mare for about half a crater diameter.
To the west-northwest of the crater on the Oceanus Procellarum is the unusual feature Reiner Gamma, a fish-shaped surface marking of ray-like material with a high albedo.
Menzel, D. H.; Minnaert, M.; Levin, B.; Dollfus, A.; Bell, B. (1971). "Report on Lunar Nomenclature by the Working Group of Commission 17 of the IAU". Space Science Reviews. 12 (2): 136–186. Bibcode:1971SSRv...12..136M. doi:10.1007/BF00171763. S2CID122125855.