What is Specification?

Legal Definition
There are different types of specifications, which generally are mostly types of documents, forms or orders or relates to information in databases. The word specification is defined as "to state explicitly or in detail" or "to be specific". A specification may refer to a type of technical standard (the main topic of this page).

Using a word "specification" without additional information to what kind of specification you refer to is confusing and considered bad practice within systems engineering.

A requirement specification is a set of documented requirements to be satisfied by a material, design, product, or service.

A functional specification is closely related to the requirement specification and may show functional block diagrams.

A design or product specification describes the features of the solutions for the Requirement Specification, referring to the designed solution or final produced solution. Sometimes the term specification is here used in connection with a data sheet (or spec sheet). This may be confusing. A data sheet describes the technical characteristics of an item or product as designed and/or produced. It can be published by a manufacturer to help people choose products or to help use the products. A data sheet is not a technical specification as described in this article.

A "in-service" or "maintained as" specification, specifies the conditions of a system or object after years of operation, including the effects of wear and maintenance (configuration changes).

Specifications may also refer to technical standards, which may be developed by any of various kinds of organizations, both public and private. Example organization types include a corporation, a consortium (a small group of corporations), a trade association (an industry-wide group of corporations), a national government (including its military, regulatory agencies, and national laboratories and institutes), a professional association (society), a purpose-made standards organization such as ISO, or vendor-neutral developed generic requirements. It is common for one organization to refer to (reference, call out, cite) the standards of another. Voluntary standards may become mandatory if adopted by a government or business contract.
-- Wikipedia
Legal Definition
Civil law. A term used in the civil law, by which is meant a person's making a new species or subject from materials belonging to another. Bouv. Inst. Theolo. ps. 1, c. 1, art. 1, ยง4, Is. 4, p. 74.

2. When the new species can be again reduced to the matter of which it was made, the law considers the former mass as still existing, and, therefore, the new species as an accessory to the former subject; but where the thing made cannot be so reduced, as in the case of wine, which cannot be again turned into grapes, there is no place for the fictio juris; and, there, the workmanship draws after it the property of the material. Inst. 2, 1, 25 Dig. 41, 1, 7, 7. See Accession; Confusion; Mixtion; and Aso & Man. Inst. B. 2, t. 2, c. 8.
-- Bouviers Law Dictionary
Legal Definition
Practice, contracts. A particular and detailed account of a thing: example, in order to obtain a patent for an invention, it is necessary to file a specification or an instrument of writing, which must lay open and disclose to the public every part of the process by which the invention can be made useful if the specification does not contain the whole truth relative to the discovery, or contains more than is requisite to produce the desired effect, and the concealment or addition was made for the purpose of deception, the patent would be void; for if the specification were insufficient on account of its want of clearness, exactitude or good faith, it would be a fraud on society that the patentee should obtain a monopoly without giving up his invention. 2 Kent, Com. 300; 1 Bell's Com. part 2, c. 3, s. 1, p. 112; Perpigna on Pat. 67; Renouard, Des Brevets d'Inv. 252.

2. In charges against persons accused of military offences, they must be particularly described and clearly expressed; this is called the specification. Tytl. on Courts Mart. 109.
-- Bouviers Law Dictionary
Legal Definition
As used in the law relating to patents and in building contracts, the term denotes a particular or detalled statement of the various elements involved. Gilbert v. U. S., 1 Ct. Cl. 34; State v. Kendall, 15 Neb. 262, 18 N. W. 85; Wilson v. Coon (C. C.) 6 Fed. 614, In military law. The clear and particular description of the charges preferred against a person accused of a military offence. Tytler, Mil. Law, 109; Carter v. Mc-Claughry, 183 U. S. 365, 22 Sup. Ct 181, 46 U Ed. 236. In the law of personal property. The acquisition of title to a thing by working it into new forms or species from the raw material; corresponding to the specificatio of the Roman law. See Lampton v. Preston, 1 J. J. Marsh. (Ky.) 462, 19 Am. Dec. 104. In practice. A detailed and particular enumeration of several points or matters urged or relied on by a party to a suit or proceeding; as, a "specification of errors," or a "specification of grounds of opposition to a bankrupt's discharge." See Railway Co. v. McArthur, 96 Tex. 65, 70 S. W. 317; In re Glass (D. C.) 119 Fed. 514.
-- Black's Law Dictionary