To Make Muddy, To Make Cloudy, To Speak Ambiguously, To Speak Vaguely
transitive verb, godan verb
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means muddy, so the verb version is to make muddy or to make cloudy.
にごす
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you: If you want to make muddy, meaning make yourself muddy, you should have your knees go (にご) first. When you have your knees go first the mud splashes all over you but you don't hurt your hands or your butt doing it.
核心をついた質問に、社長は言葉を濁した。
At the heart of the problem, the company president was vague.