As a Noun: 1. A substance which is hard and firm and remains the same shape whether it is in a container or not. English = solid. As a Verb or Adjective: 1. Of a substance, to be hard and firm and to remain the same shape whether it is in a container or not. English = (be) solid. 2. Of a substance, to feel very firm when you touch it and not to be easily bent, cut, or broken. English = (be) hard, (be) rigid, (be) firm.