Definitions:

1. (music) melodic subject of a musical composition noun
   • the theme is announced in the first measures
2. a unifying idea that is a recurrent element in literary or artistic work noun
   • It was the usual love story theme.
3. provide with a particular theme or motive verb
   • the restaurant often themes its menus

Synonyms:

• composition
• idea
• motif
• stem
• subject