what is a weed?

I can't believe how well these wildflowers are holding up - I shouldn't say "holding up", because they look exactly as perky as when I picked them.

My brother referred to them as weeds when I was marveling. And even though I also use the term occasionally, I suddenly saw there is no such thing as a weed. A "weed" is just a plant you can't identify that's in a place you don't want it to be. That's a weed.