topic is the main idea, thesis.
On top of the skin. Topical medications are used on the skin.
Gregory L. Ward has written: 'On the topicalization of indefinite NPs'
Thematic topic means something in relation to, or being a theme. Examples:Education, Country and etc.
Dong-whee Yang has written: 'Topicalization and relativization in Korean' -- subject(s): Morphology, Korean language