1. A situation, subject, or area that one has no experience with or knowledge about
The new job put him on unknown ground, as he had never worked in that industry before.
O novo emprego o colocou em terreno desconhecido, pois ele nunca havia trabalhado nesse setor antes.
2. Unfamiliar or unexplored territory, literally or figuratively
She was treading on unknown ground when she started her research in quantum physics.
Ela estava pisando em terreno desconhecido quando começou sua pesquisa em física quântica.