1. The inner and larger of the two bones in the lower leg, extending from the knee to the ankle bone alongside the fibula which is usually known as the "shinbone".
2. A bone in the lower leg of vertebrates corresponding to the human tibia.
3. The fourth segment of an insect's leg, between the femur and the tarsus.
4. The lower, often feathered segment of a bird's leg.

Tibia is a Latin word meaning both "shinbone" and "flute". It is thought that tibia refers to both the bone and the musical instrument because flutes were once fashioned from the tibia of animals.