As hard as nails and Hard-hearted

Hard-hearted and as hard as nails are semantically related. In some cases you can use "Hard-hearted" instead an adjective phrase "As hard as nails".

Hard-hearted adjective - Having or showing a lack of sympathy or tender feelings.

As hard as nails and hard-hearted are semantically related. Sometimes you can use "As hard as nails" instead an adjective phrase "Hard-hearted".