Theme

Motiv

(recurring idea)

Stamm

(grammar: stem of a word)

Thema

(subject of a talk or an artistic piece)

Thema

(music: main melody of a piece of music)

Thema

(linguistics: topic, what is generally being talked about)

Theme

(computing: collection of color schemes, sounds, artwork etc.)

Wortstamm

(grammar: stem of a word)