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.
Monopolies are on the other end of the continuum from pure competition. A monopoly consists of one firm that produces a unique product or service with no close substitutes. Entry into the market is blocked, which gives the firm market power (i.e., the power to raise price above marginal cost).