What is the meaning of Mammillary?

Resembling a breast or nipple in shape or form.

Pertaining to the nipples.

A carbonate coating formed through the precipitation of calcium carbonate onto existing rock below the water surface in cave pools.

A mammillary body, one of a pair of small round bodies, located on the undersurface of the brain, that form part of the limbic system.

Source: wiktionary.org