Lexical definitionThe lexical definition of a term, also known as the dictionary definition, is the definition closely matching the meaning of the term in common usage. As its other name implies, this is the sort of definition one is likely to find in the dictionary. A lexical definition is usually the type expected from a request for definition, and it is generally expected that such a definition will be stated as simply as possible in order to convey information to the widest audience.
Extensional and intensional definitionsIn logic, extensional and intensional definitions are two key ways in which the objects, concepts, or referents a term refers to can be defined. They give meaning or denotation to a term. An intensional definition gives meaning to a term by specifying necessary and sufficient conditions for when the term should be used. In the case of nouns, this is equivalent to specifying the properties that an object needs to have in order to be counted as a referent of the term. For example, an intensional definition of the word "bachelor" is "unmarried man".
Artificial kidneyArtificial kidney is often a synonym for hemodialysis, but may also refer to the other renal replacement therapies (with exclusion of kidney transplantation) that are in use and/or in development. This article deals mainly with bioengineered kidneys/bioartificial kidneys that are grown from renal cell lines/renal tissue. The first successful artificial kidney was developed by Willem Kolff in the Netherlands during the early 1940s: Kolff was the first to construct a working dialyzer in 1943.
