Sensei (先生) means "teacher." It's primarily used to address or refer to school teachers. However, it's also a polite honorific used for other professionals like doctors, lawyers, or experts in a particular field, showing respect for their knowledge and authority. Example: 先生、ありがとうございます。(Sensei, arigatō gozaimasu.) = Thank you, teacher.

教(きょう)師(し)や医(い)者(しゃ)など、尊(そん)敬(けい)する専(せん)門(もん)家(か)を呼(よ)ぶ時(とき)に使(つか)います。例(れい)：先(せん)生(せい)、ありがとうございます。