ˌīsō.ˈtred.əˌnȯin, -ˈtret- noun
( -s )
Etymology: is + tretinoin (herein)
: a cis isomer of retinoic acid that is a synthetic derivative of vitamin A, that inhibits sebaceous gland function and keratinization, and that is used in the treatment of severe inflammatory acne but is contraindicated in pregnancy because of implication as a cause of birth defects