The word non-concrete refers to something that is not tangible, material, or physical. Its antonyms are concrete, substantial, material, and tangible. Concrete refers to something that can be touched, seen, or felt, while substantial describes something significant or considerable. Material pertains to something that is made of matter or has a physical existence, while tangible is something that can be perceived through the senses or touch. These words are used to describe ideas, concepts, and thoughts that are real, visible and can be experienced through the senses. In contrast, non-concrete ideas are abstract, conceptual, or theoretical, existing only in the mind.