1 : the main subject that is being discussed or described in a piece of writing, a movie, etc.
The quest for power is the underlying theme of the film.
A constant theme in his novels is religion.
The playwright skillfully brings together various themes.
2 a : a particular subject or issue that is discussed often or repeatedly
The growing deficit was a dominant theme in the election.
b : the particular subject or idea on which the style of something (such as a party or room) is based
The party had a Hawaiian luau theme.
The theme of the baby's room was zoo animals. [=the baby's bedroom was decorated with pictures of zoo animals]
a theme party
a : the main melody that is repeated in a piece of music
b : THEME SONG
They played the theme from/to the movie “Rocky.”
4 US : a short piece of writing by a student on a particular subject : ESSAY
The students were assigned to write a theme on the person they admired most.