While thought may not be tangible, the human brain is a very concrete thing that can be touched and felt.

While light may not be ‘touched’ in the conventional sense, it is still concrete, since it exists in a form that can be readily perceived.

Any solid object that you can touch is concrete, unlike something abstract that you cannot interact with, such as souls, thoughts, or feelings.

Stone, dirt, water, steel, and skin are all concrete substances that can be perceived and interacted with by people.

Anything that can be proved to exist is technically concrete, even if they cannot be touched in the usual sense, such as lightning, flame, or sunlight.