The Collaborative International Dictionary
Retinoid \Ret"i*noid\, a. [Gr. ??? resin + -oid.] Resinlike, or resinform; resembling a resin without being such.
Wiktionary
a. Of or pertaining to the retina n. (context biochemistry English) Any of a class of compounds related to vitamin A
Wikipedia
The retinoids comprise a class of chemical compounds that are vitamers of vitamin A or are chemically related to it. Retinoids have found use in medicine where they regulate epithelial cell growth.
Retinoids have many important functions throughout the body including roles in vision, regulation of cell proliferation and differentiation, growth of bone tissue, immune function, and activation of tumor suppressor genes.
Research is also being done into their ability to treat skin cancers. Currently 9-cis retinoic acid may be used topically to help treat skin lesions from Kaposi's sarcoma.