大乘起信論義記 3.50

3.50

言無明者，根本無明也。能障世間業智者，顯其礙義。謂後得如量智，即上不思議業用，以無明昏迷無所分別，違此智用，名為智礙。從所障得名。

'Avidyā' refers to fundamental avidyā. 'Can obstruct the karmic cognition of the mundane world' reveals the meaning of hindrance. That is, the subsequently attained cognition of conventional reality, namely the inconceivable karmic functioning mentioned above: because avidyā is dark and confused, lacking differentiation, it opposes this cognitive function and is called the hindrance to cognition. It receives its name from what it obstructs.