Empirical evidence is a source of knowledge acquired by means of observation or experimentation. Empirical evidence is information that justifies a belief in the truth or falsity of an empirical claim. In the empiricist view, one can only claim to have knowledge when one has a true belief based on empirical evidence. This stands in contrast to the rationalist view under which reason or reflection alone is considered to be evidence for the truth or falsity of some propositions. The senses are the primary source of empirical evidence. Although other sources of evidence, such as memory, and the testimony of others ultimately trace back to some sensory experience, they are considered to be secondary, or indirect.
Wikipedia contributors, "A posteriori," Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/wiki/A_posterioriABOUT THE LATIN LANGUAGE