definition to the word that included a list of synonyms.
But as usually happens when facts get in the way of your preconceived notions you either ignore the facts or, as you are trying to do here, change the meaning of words to make them fit your arguments.
Here is another link to the definition. See in very plain sight that synonyms of the word include visible and existing.
https://www.google.com/search?safe=strict&rlz=1C9BKJA_enUS590US590&hl=en-US&ei=Z0T2WKagE8PmjwP2sKa4DA&q=concrete+definition&oq=concrete+de&gs_l=mobile-gws-serp.1.0.0i67k1j0i131k1j0l3.7728186.7728628.0.7729599.4.4.0.0.0.0.375.716.0j1j1j1.3.0....0...1c..64.mobile-gws-serp..1.3.715...0i131i67k1.JoA-2xUsyew
You do not have to hold something in your hand for it to be concrete. A birds flight, particle physics and asexual reproduction that you used as examples of abstract concepts are all very concrete. They are visible, measurable and very real.
So you took your ignorance from what was a relatively private conversation and decided to expose it to the full board. Bravo man, bravo.