n.
      - the subject of a talk, text, exhibition, etc.; a topic. 
▸Linguistics  the first major constituent of a clause, indicating the subject matter. Contrasted with rheme.
 - a recurring or pervading idea in a work of art or literature. 
▸Music  a prominent or frequently recurring melody or group of notes in a composition.
 ▸
[as modifier]
 (of music) frequently recurring in or accompanying the beginning and end of a film, play, etc.
 - 
[as modifier]
 denoting a setting given to a restaurant, pub, or leisure venue, intended to evoke a particular country, historical period, etc.:
 an Irish theme pub.
 - US a school essay written on a particular subject.
 - Linguistics  the stem of a noun or verb.
 - historical any of the twenty-nine provinces in the Byzantine empire.
 
v.
 
[
often as adj. themed]
 give a particular setting or theme to.
 
  Etymology
  ME: via OFr. from L. thema, from Gk, lit. ‘proposition’; rel. to tithenai ‘to set or place’.