All 4 Uses of

theme
in
Funny in Farsi

If you were to design a theme park around the crashed drug plane, what would you call it?
p. 177.4 *

theme park = an amusement park with one or more basic underlying ideas -- such as the "Magic Kingdom" of Disneyworld

My amoo Muhammad recently turned eighty, an event that the family celebrated with a Hawaiian-themed birthday party.†
p. 102.2

There would be no theme song, just the sound of the Metro doors opening and closing and opening and closing.†
p. 140.7

Definitions:

(1) (theme as in: theme of the novel)
a basic idea that underlies what is being said or done -- especially in a literary or artistic work
(2) (theme as in: musical theme)
the initial or primary melody of a musical composition

or

(as in "theme song") music that is most repeated in a film, television series, or other theatrical production
(3) (theme as in: wrote a 2-page theme on my summer)
an essay written by a student

(This sense of theme is much rarer in recent decades than in the past.)