The word "concrete" can have multiple meanings depending on the context. Generally, it refers to something that is tangible or specific, as opposed to abstract or theoretical. In a more technical sense, "concrete" is a building material made from a mixture of cement, water, and aggregates (like sand and gravel) that hardens into a stone-like substance. In both cases, the emphasis is on something that is solid, real, and can be perceived through the senses.
The word "concrete" comes from the Latin "concretus," which means "grown together" or "hard." The term reflects the physical nature of the material as well as the idea of coming together as a solid form.