Yes, themes is a Scrabble word!

Verb

1. Provide with a particular theme or motive

Noun

1. The subject matter of a conversation or discussion

2. A unifying idea that is a recurrent element in literary or artistic work

3. (music) melodic subject of a musical composition

4. An essay (especially one written as an assignment)

5. (linguistics) the form of a word after all affixes are removed