Name for the molecule or part of a molecule that can undergo an electronic transition to an excited state upon collision with an incident photon and then emit another photon, i.e. a fluorescent molecule. This is more specific than a chromophore, which simply absorbs light of specific frequencies without any condition on what it does in the excited state. That is to say:

A fluorophore is always a chromophore, but a chromophore isn't always a fluorophore..