1. Showing only the main shape or form of something, without details
The mountain was visible in outline against the sunset.
A montanha estava visível em esboço contra o pôr do sol.
2. In a general or summary form; covering main points without elaboration
Let me explain the project in outline before we discuss the details.
Deixe-me explicar o projeto em linhas gerais antes de discutirmos os detalhes.