This is the 7579th most frequent Russian word.
думе
"Думе" is the dative or prepositional case form of "дума," which means "thought" or "parliament" (specifically, the Russian legislative assembly).
Here, 'думаю' is a form of the verb 'думать', meaning 'to think', referring to the act of contemplation.
Я часто думаю о твоей идее.
I often think about your idea.
Here, 'Думе' refers to the Russian parliament, showcasing a proper noun usage.
Мы поговорили в Думе о законах.
We talked about laws in the Duma.
Here, 'дума' is a noun for an idea or a thought, conveying a conceptual meaning.