Turbid describes water or another liquid that is not clear — cloudy, muddy, full of tiny bits floating in it so you cannot see through. A river after heavy rain is turbid. Pond water stirred up by a foot is turbid. This is a formal, technical word: you will meet it in science writing, in reports on rivers and drinking water, on lab instruments. In ordinary talk people just say 'cloudy', 'muddy' or 'dirty'. It also has a stretched use, older and rather literary, for thoughts or feelings that are confused and troubled — 'turbid emotions'. That use is uncommon now, and if you write it, expect readers to notice it as writerly. Notice one thing about the meaning: turbid is about particles in the way, not about being poisonous. Water can be turbid and safe, or perfectly clear and dangerous. The related noun is 'turbidity', which is the word used when the cloudiness is actually measured.

混濁的（水裡懸浮著細小顆粒、看不清）。這是科學／檢驗報告用字，例如水質的「濁度」（turbidity）；日常講水髒就說 dirty、muddy 就好。