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.
Niche market. A niche market is the subset of the market on which a specific product is focused. The market niche defines as the product features aimed at satisfying specific market needs, as well as the price range, production quality and the demographics that is intended to impact. It is also a small market segment.