Sensu

Sensu is a Latin word meaning 'in the sense of'. It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular concept, but it also appears in expressions that indicate the convention or context of the usage.(...of all the possible people, only those the DA questioned, and of those, only the adult males, or one specific person only)(...as many as you like of the people that looked friendly to you in the street, even if it turns out that the appearance was misleading.) Sensu is a Latin word meaning 'in the sense of'. It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular concept, but it also appears in expressions that indicate the convention or context of the usage. Sensu is the ablative case of the noun sensus, here meaning 'sense'. It is often accompanied by an adjective (in the same case). Three such phrases are: Søren Kierkegaard uses the phrase sensu eminenti to mean 'in the pre-eminent sense'. When appropriate, comparative and superlative adjectives may also be used to convey the meaning of 'more' or 'most'. Thus sensu stricto becomes sensu strictiore ('in the stricter sense' or 'more strictly speaking') and sensu strictissimo ('in the strictest sense' or 'most strictly speaking'). Current definitions of the plant kingdom (Plantae) offer a biological example of when such phrases might be used. One definition of Plantae is that it consists of all green plants (comprising green algae and land plants), all red algae and all glaucophyte algae. A stricter definition excludes the red and glaucophyte algae; the group defined in this way could be called Plantae sensu stricto. An even stricter definition excludes green algae, leaving only land plants; the group defined in this way could be called Plantae sensu strictissimo. Conversely, where convenient, some authors derive expressions such as 'sensu non strictissimo', meaning 'not in the narrowest possible sense'. A similar form is in use to indicate the sense of a particular context, such as 'Nonmonophyletic groups are ... nonnatural (sensu cladistics) in that...' or '...computation of a cladogram (sensu phenetics)...' Also the expression sensu auctorum (abbreviation: sensu auct.) is used to mean 'in the sense of certain authors', who can be designated or described. It normally refers to a sense which is considered invalid and may be used in place of the author designation of a taxon in such a case (for instance, 'Tricholoma amethystinum sensu auct.' is an erroneous name for a mushroom which should really be 'Lepista personata (Fr.) Cooke'). A related usage is in a concept-author citation ('sec. Smith', or 'sensu Smith'), indicating that the intended meaning is the one defined by that author. (Here 'sec.' is an abbreviation of 'secundum', meaning 'following' or 'in accordance with'.) Such an author citation is different from the citation of the nomenclatural 'author citation' or 'authority citation'. In biological taxonomy the author citation following the name of a taxon simply identifies the author who originally published the name and applied it to the type, the specimen or specimens that one refers to in case of doubt about the definition of a species. Given that an author (such as Linnaeus, for example) was the first to supply a definite type specimen and to describe it, it is to be hoped that his description would stand the tests of time and criticism, but even if it does not, then as far as practical the name that he had assigned will apply. It still will apply in preference to any subsequent names or descriptions that anyone proposes, whether his description was correct or not, and whether he had correctly identified its biological affinities or not. This does not always happen of course; all sorts of errors occur in practice. For example, a collector might scoop a netful of small fish and describe them as a new species; it then might turn out that he had failed to notice that there were several (possibly unrelated) species in the net. It then is not clear what he had named, so his name can hardly be taken seriously, either s.s. or s.l.