retinoid adjective 1noun 1forms 3 adjective1 •(no longer used, rare) Pertaining to or resembling a resin. noun1 •Any of a class of compounds whose structure or effects on the body resemble retinol (vitamin A).Tests on the two retinoids, combined with computer modelling, showed that the compounds killed not only normal MRSA cells, but dormant, or “persister”, cells too. — 2018 formsretinoids · more retinoid · most retinoid