1N-COUNT （沙漠中的）绿洲 An oasis is a small area in a desert where water and plants are found. （沙漠中的）绿洲
2N-COUNT （恶劣环境中的）宜人之地，乐土；（不愉快情形下的）开心之时，乐事 You can refer to a pleasant place or situation as an oasis when it is surrounded by unpleasant ones. （恶劣环境中的）宜人之地，乐土；（不愉快情形下的）开心之时，乐事
The immaculately tended gardens are an oasis in the midst of Cairo's urban sprawl. [+ in]