Mar 18, 2011 · "why" can be compared to an old Latin form qui, an ablative form, meaning how. Today "why" is used as a question word to ask the reason or purpose of something. This use.
Why is used here as an interjection. According to Merriam-Webster: —used to express mild surprise, hesitation, approval, disapproval, or impatience <why, here's what I was looking for>.
