What is the meaning of idiomatic expression a throw?

The phrase "a throw" is not typically used as an idiomatic expression. However, depending on the context, it could be interpreted in a few ways:

1. "A Throw of the Dice": This is an idiomatic expression meaning a chance, a gamble, a risk. It refers to the random outcome of rolling dice in a game.

2. "A Throwaway Item": This describes something of little value or importance, easily discarded.

3. "A Throw of the Head": This could be interpreted as a quick glance or a sudden movement of the head.

4. "A Throw of the Switch": This refers to an action that instantly changes something, similar to flipping a switch.

5. "A Throw of the Blanket": This could mean to quickly cover yourself with a blanket, like a reflex action in the cold.

If you provide more context or a sentence where you encountered "a throw," I can give you a more accurate interpretation.