extramural vs topical

extramural

adj
  • Describing teaching of students who are not resident at such an institution. 

  • Taking place outside the walls of an institution, especially a school or university. 

topical

adj
  • Relating to a particular topic or subject. 

  • Arranged according to topic or theme; thematic. 

  • Applied to a localized part of the body. 

  • Local to a particular place 

  • Applied externally (to the surface of the skin or eye). 

  • Relating to a topic or subject of current interest. 

noun
  • A joke dealing with current events or topical subjects. 

  • A postage stamp depicting a particular theme or subject (such as birds or trains), potentially sought out by topical stamp collectors. 

  • A substance, especially a medication, applied externally (to the surface of the skin or eye). 

  • A topical anaesthetic. 

How often have the words extramural and topical occurred in a corpus of books? (source: Google Ngram Viewer )