1. to master (a skill)
すでに、キッチンの使い方はマスターしましたから。I have already mastered how to use the kitchen.
2. proprietor; manager; owner; barkeeper
マスターが泊まってけって言ってたよ。The owner said you should stay the night.
3. leader; chief; head
4. master (of arts, science, etc.)
5. master (recording)
6. master (device)
7. master (data)