n. A person who scientifically reveals a new species by technically describing its characteristics and particularly how it differs from other species.
the GNU version of the Collaborative International Dictionary of English
n. One who describes.
The Century Dictionary and Cyclopedia
n. One who describes or depicts by words or signs.
Word Usage
"And a monk who considers a horse excellent, whatever his natural forms, can only see him as the auctoritates have described him, especially if "- and here he smiled slyly in my direction -" the describer is a learned Benedictine. ""