Better to listen, because that's what the definitions would then imply. If you don't listen closely and repeatedly, no words will help. So what is jazz? One answer is the album today. Pianist-composer Leslie Pintchik and her ensemble put together a new program of music you could profitably hear to help you on your way to a mental construct of "jazz". It's called In the Nature of Things (Pintch Hard 002). We've covered another of hers here if you want to look that up.
Well this is modern jazz, not so much commercial (which to me would be a negative most of the time) as current. Leslie is at the piano, Steve Wilson presides often enough on alto and soprano saxes, Ron Horton brings his trumpet and flugelhorn, Scott Hardy is on acoustic bass, Michael Sarin on drums, and Satoshi Takeishi on percussion.
They do one standard for the measure and the rest are Pintchik originals. These are well-made. They have chord changes of interest which Leslie and company solo over with skill and finesse. The head melodies are fetching and well-voiced for the ensemble. Leslie has a harmonically rich, rhythmically lively piano style that bears your ear-attention, most definitely.
It is a pleasure, a treat to hear. And you know what? It's like jazz, you dig? As in blow (your horn). It's a good example of the middle-ground today.