calf
A baby cow or the back part of your lower leg.
A calf (plural: calves) is a baby cow, though the word applies to the young of several large animals. On a dairy or cattle farm, you'll see calves nursing from their mothers or drinking from bottles. Baby elephants, whales, and even giraffes are also called calves.
Calves are born able to stand and walk within hours, though they stay close to their mothers for protection and milk. A newborn calf might weigh 60 to 100 pounds, which sounds heavy until you remember that adult cows can weigh over 1,000 pounds. Farmers take special care of calves because they're vulnerable to cold weather and illness in their early weeks.
The word has a completely separate meaning: your calf is also the back part of your lower leg, the muscular area between your knee and ankle. When you walk, run, or jump, your calf muscles do much of the work. If you've ever gotten a charley horse (a painful muscle cramp), it probably happened in your calf. Dancers and athletes develop strong calf muscles from constant use, which is why their lower legs often look especially muscular and defined.