reflectionThe process whereby radiation (or other waves) incident upon a surface is directed back into the medium through which it traveled.
reflection coefficient (RC)The ratio of the amplitude of the reflected wave and the amplitude of the incident wave. 2.
reflection lossAt a discontinuity or impedance mismatch, e.g., in a transmission line, the ratio of the incident power to the reflected power.
reflective array antennaAn antenna, such as a billboard antenna, in which the driven elements are situated at a predetermined distance from a surface designed to reflect the…
ReflectivityThe measure of the efficiency of a radar target in intercepting and returning Electro Magnetic Energy.
ReflectorA component of a solar energy facility that reflects incident sunlight to a desired location or component within the facility, allowing it to be converted…
refracted rayA ray that undergoes a change of velocity, or in the general case, both velocity and direction, as a result of interaction with the material medium in…
RefractionThe change in direction of a ray of light when it passes through one media to another with differing optical densities.
refractive index (η, n)Of a medium, the ratio of the velocity of propagation of an electromagnetic wave in vacuum to its velocity in the medium. Synonym index of refraction.
refractive index contrastIn an optical fiber, a measure of the relative difference in refractive index of the core and cladding.
refractive index profileOf the cross section of an optical fiber, the description, i.e., plot, of the value of the refractive index as a function of distance from the fiber axis…
reframing timeThe time interval between the instant at which a valid frame-alignment signal is available at the receiving data terminal equipment and the instant at…
refreshTo reproduce, repeatedly, a display image on a display surface, so that the image remains visible.
refresh packetsSignaling packets that are transmitted on a periodic basis across a permanent virtual circuit in the direction of transmission from the channelized side…
Refresh TagSee the paragraph about HTTP_EQUIV under Meta Tag.
RefreshingThis term can refer to periodic retensioning of tape, or the rerecording of recorded information onto the same tape (or different tape) to refresh the…
regenerationIn biology, regrowth of damaged or destroyed tissue or body part.
regenerative feedbackFeedback in which the portion of the output signal that is returned to the input has a component that is in phase with the input signal.
regenerative repeaterA repeater, designed for digital transmission, in which digital signals are amplified, reshaped, retimed, and retransmitted. Synonym regenerator.
regeneratorSynonym regenerative repeater. 2. A device that reconstructs and retransmits a received pulse train. [T1.403-1989]
regionA coverage feature class used to represent a spatial feature as one or more polygons. Many regions can be defined in a single coverage.
Regional Bell Operating Company (RBOC)Historically, one of the seven holding companies formed by divestiture by the American Telephone and Telegraph Company of its local Bell System operating…
Regional Defense System (RDS)That portion of the SDS that provides defense for a specific geographic region, such as the European Theater.
regional disasterA disaster, such as an earthquake or hurricane, that affects a large region. Local, campus, and proximate metropolitan clusters are less likely to protect…
Regional Operations Center (ROC)A group of fixed and/or mobile centers with OPCON over allocated ground based sensors and weapons. 246
Regions - US East, US West, GovCloudAmazon’s way of classifying multiple geographic areas hosting EC2 world-wide. Each AWS Region is a separate geographic area.
registera record book; it is also the county official charged with keeping record copies of legal instruments such as property deeds and other records.
registered jack (RJ)Any of the series of jacks, described in the Code of Federal Regulations, Title 47, part 68, used to provide interface to the public telephone network.
registered tableA DBMS table which is part of an ArcStorm database is said to be 'registered' with the database.
RegistrarA company which allows you to register domain names.
RegistrationLining up a forms image to determine which fields are where. Also, entering pages into a scanner such that they are correctly read.
registration agent (RA)An application process that receives an RRP (registration request protocol), message from the registration manager signaling it to start automatic…
registration authorityIn networking, an organization that performs registration for information objects and devices. [After 2382-pt.35]
Registration Authority (RA)A trusted entity that establishes and vouches for the identity of a subscriber to a CSP.
registration manager (RM)An application process responsible for contacting the registration agent using the RRP (registration request protocol) to start automatic registration of…
registration of a templateOfficial approval of a template by NARA, and placement of the template in the ERA template repository. Once registered, the template can be used.
registration procedureIn networking, the procedure for performing registration or for amending or deleting existing registrations. [2382-pt.35]
registryAn infrastructure that enables the building, deployment, and discovery of Web services.
registry providerAn implementation of a business registry that conforms to a specification for XML registries (for example, ebXML or UDDI).
RegradeTo determine that certain classified information requires, in the interests of national security, a higher or lower degree of protection against…
regular expressionA single entity with various interpretations, like an elephant. To a computer scientist, it's a grammar for a little language in which some strings are…
regular expression modifierAn option on a pattern or substitution, such as /i to render the pattern case insensitive. See also "cloister".
regular fileA "file" that's not a "directory", a "device", a named "pipe" or "socket", or a "symbolic link".
ReinclusionIf a site has been penalized for spamming they may fix the infraction and ask for reinclusion.
rejectAn option during approval to prevent a draft document from being published and return it to authors for additional editing. See also: approval
rekeyingThe changing of one or more keys that are used for either COMSEC or TRANSEC functions.
relateAn operation that establishes a temporary connection between corresponding records in two tables using an item common to both (i.e., relate key).
relate keyThe common set of columns used to relate two attribute tables. See also relate, primary key and foreign key.
relational databaseA method of structuring data as collections of tables that are logically associated to each other by shared attributes.
Relational database management system (RDBMS)(RDBMS)A database management system with the ability to access data organized in tabular files that can be related to each other by a common field (item).
Relational Database Service (RDS)(RDS)A web service that allows users to set up, operate and scale a relational database in the cloud.
relational joinThe operation of relating and physically merging two attribute tables using their common item.
relational operatorAn "operator" that says whether a particular ordering relationship is "true" about a pair of operands.
relational operatorsOperators, such as <, >, <=, >=, == and !=, that produce a boolean result, as part of a boolean expression.
relationship fieldA virtual field of an entity bean having container-managed persistence; it identifies a related entity bean.
relative addressIn computer and data processing programming, an address that is expressed as a difference in relation to a base address. [After Weik '96]
Relative boostingThis enables a document to always be displayed among the first 20 documents in the result list, provided a user searched with a specific query.
Relative Distinguished name (RDN)The part of the name of an object that is an attribute of the object itself. The attribute that provides the RDN for an object is referred to as the…
relative errorThe ratio of an absolute error to the true, specified, or theoretically correct value of the quantity that is in error.
relative filenameA filename whose full path is relative to some point within a file system tree - often the current working folder (directory). For instance ../bin/javac.
Relative humidity (RH)The amount of water in the air relative to the maximum amount of water that the air can hold at a given temperature.
relative IDThe portion of a security identifier (SID) that identifies a user or group in relation to the authority that issued the SID.
Relative ID (RID)The master service that is responsible for the assignation of relative IDs to other domain controllers within the domain.
relative identifierThe portion of a security identifier (SID) that identifies a user or group in relation to the authority that issued the SID.
Relative LinkA link which shows the relation of the current URL to the URL of the page being linked at.
relative transmission levelThe ratio of the signal power, at a given point in a transmission system, to a reference signal power.
RelayAllows an SMTP server to accept any email destined for other hosts and re-deliver that mail to the proper host, much like a feild and track relay race…
relay configurationAn operating configuration in which a circuit is established between two stations via an intermediate relay station.
release nodeThe initial destination of a call from a pivot node. Note: A service or network capability provided at the release node, after determining the call should…
release prefix[A] prefix appended to the short title of U.S.-produced keying material to indicate its foreign releasability.
release timeThe time interval between (a) the instant that an enabling signal (as in a vogad or echo suppressor) is discontinued, and (b) the instant at which…
release timerA timer that specifies the period of time the network will wait for a release from the user after informing the user of a failure condition such as busy.
Relevancethe likelihood that a given web page will be of interest or useful to a search engine user for a keyword search.
Relevance or Relevance rankingRelevancy is the measure of how well the indexed page answers the question. Only the searcher can actually define how relevant a document is, in relation…
RelevancyA measure of how useful searchers find search results. Many search engines may also bias organic search results to informational resources since…
Relevancy AlgorithmThe method a search engine or directory uses to match the keywords in a query with the content of each web page, so that the web pages found can be…
ReliabilityThe consistency of a measure or question in obtaining very similar or identical results when used repeatedly; for example, if you repeated a blood test…
Reliability and Maintainability (R&M)Reliability and maintainability design parameters are key factors in the design of affordable and supportable systems.
reliability assessmentThe process of determining whether existing hardware, firmware, or software has achieved a specified level of operational reliability. 2.