(noun)
some effect or action that is exerted or performed in response to something else, a reaction or a reciprocal action, for example the recoil that something experiences after an impact;
e.g. She expects that there will be no repercussion to her harsh words.
(noun)
in old usage, a reflection, especially an echo (a reverberation, i.e. vibrations that continue to be reflected off various surfaces);
e.g. He heard the repercussion of his own voice from the hills.