"A network software product that allows computers or networks running dissimilar protocols to communicate, providing transparent access to a variety of foreign database management systems (DBMSs). A gateway moves specific database connectivity and conversion processing from individual client computers to a single server computer. Communication is enabled by translating up one protocol stack and down the other. Gateways usually operate at the session layer." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)
"Connectivity software that allows two or more computer systems with different network architectures to communicate." (Sybase, "Glossary", 2005)
"A generic term referring to a computer system that routes data or merges two dissimilar services together." (Paulraj Ponniah, "Data Warehousing Fundamentals for IT Professionals", 2010)
"A software product that allows SQL-based applications to access relational and non-relational data sources." (DAMA International, "The DAMA Dictionary of Data Management", 2011)
"An entrance point that allows users to connect from one network to another." (Linda Volonino & Efraim Turban, "Information Technology for Management" 8th Ed., 2011)
[database gateway:] "Software required to allow clients to access data stored on database servers over a network connection." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures" 2nd Ed., 2012)
"A connector box that enables you to connect two dissimilar networks." (Faithe Wempen, "Computing Fundamentals: Introduction to Computers", 2015)
"A node that handles communication between its LAN and other networks" (Nell Dale & John Lewis, "Computer Science Illuminated, 6th Ed.", 2015)
"A system or device that connects two unlike environments or systems. The gateway is usually required to translate between different types of applications or protocols." (Shon Harris & Fernando Maymi, "CISSP All-in-One Exam Guide" 8th Ed., 2018)
"An application that acts as an intermediary for clients and servers that cannot communicate directly. Acting as both client and server, a gateway application passes requests from a client to a server and returns results from the server to the client." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)