The dictionary definition I like best is the following..............
The dictionary definition doesn't come close to answering the question. If angels and other spirit creatures exist, what is this spirit stuff comprised of?
I believe that God is the creator, and the spark of life, spirit, is in all living things and causes them to grow and age.
What is this God stuff made of is the question. Your answer is, at best, a metaphor, a stand in for "I don't understand how life got started".
Many people cannot make higher order abstractions and think in only concrete terms, so they cannot fully understand higher order abstractions. This satisfies my curiosity of what spirit is.
How sad. Another example of relgious thinking being a though stopping process. I full realize that this was an attempt at a clever insult, but instead it showed that, yet again, when God and religion get involved, people turn their brain off. It had the opposite of the intended effect.