This crater has a slender inner wall and an interior floor that has been resurfaced by basalticlava. The rim is somewhat worn and irregular, but retains a generally circular shape and is not overlaid by any smaller craters of significance. The interior floor is marked only by a multitude of tiny craters, and a small, unnamed crater in the south-southeastern section.
The exterior of the crater consists of the outer rampart and sections of rough terrain. This in turn is nearly enclosed by lava-flooded sections of the surface belonging to the Mare Australe. To the east of Lamb is Lamb G, a somewhat smaller, lava-flooded formation.
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.