Your nostrils are the two openings at the end of your nose.
e.g. Keeping your mouth closed, breathe in through your nostrils.
Your heel is the back part of your foot, just below your ankle.
e.g. She’s got a sore heel.
Your toenails are the thin hard areas at the end of each of your toes.
e.g. Margaret was painting her toenails.
A woman’s breasts are the two soft, round parts on her chest that can produce milk to feed a baby.
e.g. When a woman becomes pregnant her breasts tend to grow larger.
e.g. The benefits of breast milk for babies are numerous.
The nipples on someone’s body are the two small pieces of slightly hard flesh on their chest. Babies suck milk from their mothers’ breasts through their mothers’ nipples.
e.g. Sore nipples can inhibit the milk supply.