On the tips of the toes, in a state of eager anticipation or careful movement.
From 'a-' (on) + 'tiptoe', combining Old English elements with the modern phrase 'on tiptoe' meaning to walk quietly on the ends of one's toes.
This word captures the physical and emotional state of waiting with excitement—your body literally reflects your anxious anticipation, which is why writers use it to describe both movement and suspense.
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