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1. To whistle loudly up or along the length of something. I whistled up the river to let them know where I was. Tom whistled up the tree, and his brother lowered down the rope ladder leading to their fort.
2. To call or summon one or more people or animals by whistling. A noun or pronoun can be used between "whistle" and "up." She whistled up the horses, and they trotted over to her straight away. The drill sergeant whistled us up in front of the mess hall.
Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.