Meaning
軟骨 (なんこつ, Nankotsu) is Cartilage, a Japanese food (viscera).
What is Cartilage?
Nankotsu (cartilage) doesn't have a particularly strong flavor, but grilled cartilage is popular for its unique crunchy texture. There are two varieties of cartilage that are commonly served: that which connects thigh and shin muscle (pictured here) and that which comes before the breast bone, which is called yagen nankotsu (薬研軟骨). The word "薬研" refers to a mortar used to grind drugs. Seasoned with a little salt, a squeeze of lemon, or a slightly sweet sauce, nankotsu is a staple of just about any yakitori or yakiniku restaurant in Japan.