What is the term used for casting off a hawk from the fist?

The term for casting off a hawk from the fist is commonly referred to as "to throw off." This action involves releasing the hawk from the falconer's glove, allowing it to fly freely. The term reflects the straightforward nature of the action, where the falconer literally throws or releases the bird into the air.

The other terms listed, while they may relate to falconry or have specific meanings associated with training or handling birds of prey, do not correctly describe the action of releasing a hawk from the fist. "To truss" typically involves securing or tying the bird down, and "to tower" refers to a bird's climbing or soaring behavior after being released. "To throw-up" does not have an established meaning within the context of falconry.