Large-scale structure of the Universe
A baryon is a particle consisting of three quarks/antiquarks (In other words, a hadron). Therefore, baryonic matter can in very rather simple terms be referred to as anything consisting of particles consisting of three standard model based particles. By extension, this includes atoms,groups of atoms(molecules) and the various large scale structures they form such as humans,the Earth, stars etc. Baryonic matter in much simpler commutative terms is what can interact electromagnetically, gravitationally and via the weak force and the strong nuclear force.