(a) tamamen yanlış (yolda), yanılmış. The police were way off base when they tried to accuse her of
the theft. Your idea is completely off base : Fikriniz tamamıyla yanlış. (b) hazırlıksız. She caught me off base with that question: O soru ile beni hazırlıksız yakaladı (gafil avladı).
English-Turkish translations from the Atalay Dictionary, First Edition