Slush is half-melted snow lying dirty on the ground. Grey, wet, and it gets into your shoes.
It arrives a day after the snow and is thoroughly unloved. The adjective slushy describes both the ground and, quite separately, sentimental films and songs, since a slushy romance is sickly sweet. A slush fund is a reserve of money kept for questionable purposes, from an old naval practice of selling waste fat. American English has the slush pile, meaning unsolicited manuscripts nobody has read yet.
1nounslushPartly melted, dirty snow.
“The pavements were ankle deep in slush.”
May be a variant of sludge or imitative of the sound like slosh. Perhaps a confluence of both influences.
Etymology from Wiktionary, CC BY-SA