Entry 1 sense Webster, 1913 Subtilism · Sub·til·ism · IPA /ˈsʌbtɪlɪzəm/ 01 n. The quality or state of being subtile; subtility; subtlety. 1. The quality or state of being subtile; subtility; subtlety. “The high orthodox subtilism of Duns Scotus.” — Milman.