It’s tough to nail down the right definition, since it was initially a Marxist term of derision that was later claimed by radical free market proponents.

I try to keep that in mind to check my own preference to equate capitalism with purely free markets.

So, mine is probably something like “A system where private owners decide how to utilize scarce resources, rather than a collective decision making process.”

That leaves the door open for some of the forms of capitalism that we may not like and that are often conflated with the version(s) we do like.