Retinoid: 1. Vitamin A (retinol) or a naturally occurring or synthetic substance chemically related to it. (Retinoid literally means "like retinol.") 2. In ophthalmology, resembling the retina. From Healthy Resources 11 Ways to Treat Your Psoriasis NaturallyFood Dos and Don’ts to Tame Inflammation7 Germy Places You Probably Touch Every Day Featured Centers What Are the Best PsA Treatments for You?Understanding Biologics 10 Things People With Depression Wish You Knew Health Solutions From Our Sponsors