起信論所說。分別根本無明之相狀者。對於枝末無明之六麤而謂為三細：一、無明業相，業者動作之義，不達於一法界之理，真心之初動作者。二、能見相，既有由動作，有能見之相。三、境界相，有能見之相，則必有所見之相。此三相中動作就體，能見所見就用。體用不離，一時具三相。此相用至為微細，故稱為三細。出於起信論義記中末。
The three refined, or subtle conceptions, in contrast with the 六麤 cruder or common concepts, in the Awakening of Faith起信論. The three are 無明業相 "ignorance", or the unenlightened condition, considered as in primal action, the stirring of the perceptive faculty; 能見相 ability to perceive phenomena; perceptive faculties; 境界相 the object perceived, or the empirical world. The first is associated with the 體corpus or substance, the second and third with function, but both must have co-existence, e.g. water and waves. v. 六麤.