An obscure point; a wholly or partially unintelligible expression, piece of writing, etc.

Grammar and Rhetoric. A confused arrangement of words in a sentence, obscuring the meaning.

Confused or worthless discourse. Also, writing of this nature.

Loose volatile matter; a mass of fine, light, fluffy particles.

figurative and in extended use (chiefly from sense 2): something ill-defined or insubstantial; a hazy mass or cloud.

A difficult passage for translation or explanation.