Specific language impairment (SLI) is diagnosed when a child's language does not develop normally and the difficulties cannot be accounted for by generally slow development, physical abnormality of the speech apparatus, autism spectrum disorder, acquired brain damage or hearing loss.
Perfect competition. A perfectly competitive market is a hypothetical market where competition is at its greatest possible level. Neo-classical economists argued that perfect competition would produce the best possible outcomes for consumers, and society.
The level of competition in a market can be described on a spectrum from purely monopolistic, in which a single company is the sole producer of a particular good or service, to purely competitive, in which a sufficient number of firms are of relatively equal size such that no one company can influence the market in any way.