- [countable]
a part of the sea, or of a large lake, partly surrounded by a wide curve of the land （海或湖的）湾 
the Bay of Bengal 孟加拉湾 Hudson Bay 哈得孙湾 a magnificent view across the bay 海湾一带的壮观景象 apartments overlooking the bay 俯瞰海湾的公寓
Oxford Collocations Dictionaryadjective- sheltered
- shallow
- sandy
- …
- overlook
- across the bay
- [countable]
a marked section of ground either inside or outside a building, for example for a vehicle to park in, for storing things, etc. 分隔间（户外或室内的，用以停放车辆、存放货物等） Oxford Collocations Dictionaryadjective- cargo
- docking
- hangar
- …
- [countable]
a curved area of a room or building that sticks out from the rest of the building （建筑物的）突出结构 - [countable]
a horse of a dark brown colour 深棕色马；栗色马 - [countable]
a deep noise, especially the noise made by dogs when hunting （尤指猎犬捕猎时的）低沉吠声 - (also bay tree)[countable]
a small tree with dark green leaves with a sweet smell that are used in cooking 月桂树，甜月桂（叶子可作香料） - [uncountable]
the leaves of the bay tree, used in cooking as a herb 月桂（用作香料） 
Word Originnoun sense 1 late Middle English: from Old French baie, from Old Spanish bahia, of unknown origin. noun senses 2 to 3 late Middle English: from Old French baie, from baer ‘to gape’, from medieval Latin batare, of unknown origin. noun sense 4 Middle English: from Old French bai, from Latin badius.
Idioms
at bay
when an animal that is being hunted is at bay, it must turn and face the dogs and hunters because it is impossible to escape from them （猎物）被围困，被迫作困兽之斗
hold/keep somebody/something at bay
to prevent an enemy from coming close or a problem from having a bad effect 不让（敌人）接近；防止（问题）恶化