[n] a strong hard building material composed of sand and gravel and cement and water
[adj] capable of being perceived by the senses; not abstract or imaginary; "concrete objects such as trees"
[adj] formed by the coalescence of particles
[v] form into a solid mass; coalesce
[v] cover with cement; "concrete the walls"
A concrete poem is one that takes the shape of the object it describes. This is different from a Shape poem, in that a Shape poem does NOT have to take the shape of the object it describes.
factual, objective, real, solid, tangible
building material, cement, cover, existent, ferroconcrete, paving material, practical, reinforced concrete, sand, solidify