Entry 1 sense Webster, 1913 Retinoid /rĕt'-ĭn-oid/ · Ret·i·noid · IPA /rˈɛtɪnɔɪd/ 01 a. Resinlike, or resinform; resembling a resin without being such. 1. Resinlike, or resinform; resembling a resin without being such.