to move with a splashing motion <the baby gurgled contentedly as the water sloshed gently around him in the bathtub>
to cause (something liquid or mushy) to move along in sheets <while painting the Windsor chair, he carelessly sloshed paint all over the adjacent wall>
Seen & Heard
What made you want to look up slosh? Please tell us where you read or heard it (including the quote, if possible).