topical

adj. local, regional; current, popular; of topics; of or relating to topics, arranged by subjects and topics; superficial, external; (Medicine) applied externally, applied to to a particular place on the body

n. (Philately) collection of different stamps dealing with the same topic

In medicine, a topical medication is applied to body surfaces such as the skin or mucous membranes such as the vagina, penis, anus, throat,  eye or the ear. Some hydrophobic chemicals such as steroid hormones can be absorbed into the body after being applied to the skin in the form of a cream, gel or lotion.  Transdermal patches have become a popular means of administering some drugs for birth control, hormone replacement therapy, and prevention of motion sickness.
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Adjective
1. pertaining to the surface of a body part; "a drug for topical (or local) application"; "a topical anesthesia"
(similar) local
(classification) medicine, medical specialty
2. of or relating to or arranged by topics; "a detailed record on both a chronological and a topical basis"
(pertainym) topic, subject, issue, matter
3. of interest at the present time; "a topical reference"; "a topical and timely study of civil liberty"
(similar) current

(n.)
Resembling a topic, or general maxim; hence, not demonstrative, but merely probable, as an argument.
  

(n.)
Pertaining to, or consisting of, a topic or topics; according to topics.
  

(n.)
Of or pertaining to a place; limited; logical application; as, a topical remedy; a topical claim or privilege.
  

On the surface of the body.