The medical root word for hard is "sclero-" or "sclera-".
The medical root word "carpo" refers to the wrist.
The medical root word 'derma' refers to the skin.
The medical root word encephalo refers to the brain.
The medical root word "entero" refers to the intestines.
The medical root word "ophthalmo" refers to the eyes.
The medical root word 'cantho' refers to the canthus (angle at either end of slit between eyelids).
The medical root word 'ano' refers to the anus.
The medical root word 'arterio' refers to the artery.
The medical root word 'blepharo' refers to the eyelid.
The medical root word 'capit' refers to the head.
The medical root word 'cleido' refers to the collarbone.
The medical root word 'cyto' refers to the cell.
The medical root word 'gingivo' refers to the gums.
The medical root word 'gnatho' refers to the jaw.
The medical root word 'histio' refers to the tissue.
The medical root word 'linguo' refers to the tongue.
The medical root word 'lympho' refers to the lymph.