the GNU version of the Collaborative International Dictionary of English
n. One who, or that which, reveals.
The Century Dictionary and Cyclopedia
n. One who reveals or discloses; one who or that which brings to light, shows, or makes known.
Word Usage
"The delusion that he had actually achieved this feat did no harm at first, because if people's views are sound, about evolution or anything else, it does not make two straws difference whether they call the revealer of their views Tom or Dick."