hard (not easy to bend, cut, or break; not soft): He fell on hard ground and broke his leg.
solid (hard and stable in shape; not liquid or gas): Ice is water in a solid state.
firm (solid but not completely hard): I sleep on a firm mattress. Freeze it until it is firm but not rock-solid.
stiff (firm and not easily bent): Scrape off the rust with a stiff brush.
rigid (not easy to bend or change in shape; not flexible): The table was made of rigid plastic.
