the GNU version of the Collaborative International Dictionary of English
ad. In a topical manner; with application to, or limitation of, a particular place or topic.
The Century Dictionary and Cyclopedia
With reference to topics; also, with regard or application to a particular place, spot, subject, etc.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
ad. to a restricted area of the body
Word Usage
"Some tricks of the trade that may be discussed include Cayenne's ability to sooth pain and itching sensations when applied topically, which is sure to help students take better care of themselves when on a tight budget."