noun
fatty tuna; tuna belly
Refers to the fatty belly cut of tuna, prized in sushi and sashimi. Often contrasted with 赤身 (lean tuna).
お寿司屋さんで、とろを一貫注文した。
At the sushi restaurant, I ordered one piece of fatty tuna.
大トロは特に脂がのっていて美味しい。
Extra-fatty tuna belly is especially rich and delicious.
The origin is uncertain; possibly related to the onomatopoeic とろとろ (melting, soft), describing the texture of the fatty meat.