This is the 11844th most frequent German word.
theo
"Theo" is typically a short form of the German name "Theodor" and does not have a standalone meaning in German apart from being a name.
Here, 'Theo' is used as a proper name, identifying a specific individual.
Theo ist ein kluger Student.
Theo is a clever student.
In this sentence, the term 'theoretisch' is used, derived from 'theo' as a root form, relating to theory.
Das Buch ist nur theoretisch interessant.
The book is only theoretically interesting.
Here, 'theologische' is an adjective derived from 'theo,' pertaining to theology.