Tenor has several meanings:

1. A type of male singing voice that's higher than most men's normal speaking voices. In a choir or musical group, the tenor sings the higher male parts, above the baritone and bass singers but below the female altos and sopranos. Many famous opera singers and pop stars are tenors. When Pavarotti sang, his powerful tenor voice could fill an entire concert hall.
2. The general character, mood, or direction of something. When someone asks about the tenor of a conversation, they want to know whether it was friendly, tense, serious, or playful. A teacher might notice the tenor of her classroom shifting from excited to focused as students settle into their work. The tenor of a book might be hopeful, even when describing difficult situations.
3. A saxophone that's medium-sized, lower than an alto sax but higher than a baritone sax. Jazz musicians often play the tenor saxophone, which has a rich, warm sound. The tenor sax became famous in jazz music through players like John Coltrane and Sonny Rollins.