oberer meaning and definition in german

Since the adjective is already semantically comparative in its positive form, the grammatical comparative forms are very rare and heard in the vernacular only. They might be used to mean “even more above”. For example: Mein Portmonee ist in der oberen Schublade. − In dieser? − Nein, in der noch obereren. (“My purse is in the upper drawer.” – “This one?” − “No the one above that.”)
The superlative forms are perfectly normal, being the same as English uppermost.