Liquid secreted from the nose; nasal mucus or discharge (colloquially: snot).
風邪で鼻汁が止まらないのでティッシュが手放せない。
My nose keeps running because of a cold, so I can't be without tissues.
赤ちゃんは鼻汁が多いと呼吸が苦しそうに見えることがある。
When babies have a lot of nasal discharge, they can sometimes look like they're having trouble breathing.
花粉症の季節は鼻汁やくしゃみが増える。
During pollen season, nasal discharge and sneezing increase.