areola

n. halo; dark band of skin which surrounds a nipple; plant cell; very small area

In anatomy, the term areola, plural areolae, (diminutive of Latin area, "open place") is used to describe any small circular area such as the colored skin surrounding the nipple. While it is most commonly used to describe the pigmented area around the human nipple (areola mammae), it can also be used to describe other small circular areas such as the inflamed region surrounding a pimple.
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Areola /are·o·la/ pl. are´olae [L.] 1. any minute space or interstice in a tissue. 2. a circular area of different color surrounding a central [more]Areola - Community and Resources

Noun
1. small space in a tissue or part such as the area between veins on a leaf or an insect's wing
(hypernym) interstice
2. small circular area such as that around the human nipple or an inflamed area around a pimple or insect bite
(synonym) ring of color
(hypernym) area, region
(part-holonym) breast, bosom, knocker, boob, tit, titty

n. areola, dark band of skin which surrounds a nipple; very small area; plant cell