theme

theme /ˈθiːm/ noun
plural themes
theme
/ˈθiːm/
noun
plural themes
Britannica Dictionary definition of THEME
[count]
1 
: the main subject that is being discussed or described in a piece of writing, a movie, etc.
2 
a  : a particular subject or issue that is discussed often or repeatedly
b  : the particular subject or idea on which the style of something (such as a party or room) is based
3 
music
a  : the main melody that is repeated in a piece of music
b  : theme song
4 
US : a short piece of writing by a student on a particular subject : essay

— themed

/ˈθiːmd/ adjective, always used before a noun