The word "concrete" can mean two things: as a noun, it refers to a hard building material made of gravel, sand, and cement; as an adjective, it describes something real, specific, or solid, opposite to abstract or vague things. Full definition
The law is full of concrete examples of shifting levels of proof and burdens of proof depending upon what kind of risks are at stake and who is at risk from potentially risky behavior. (ethicsandclimate.org)
This is the head - job you need to set in concrete in your mind before you walk through that door. (sciencemag.org)
It is very popular for use with concrete in floor heating systems, swimming pool heating, or any other application where large quantities of hot water are required. (ahac.ie)