testbed diagram
Testbeds as a process (click image to enlarge)

What's a Testbed?

From Merriam Webster's 11th Collegiate Dictionary:

test bed (1917: noun): broadly: any device, facility, or means for testing something in development.

From Dabberdt et al. in BAMS 2005

Test beds defined. The TBWG (testbeds work group) developed the following consensus definition of a test bed. The "blank" in the following paragraph represents a type of phenomenon or forecast problem, for example, air quality, hurricane, hydrometeorology, or severe weather:

A testbed is a working relationship in a quasi-operational framework among measurement specialists, forecasters, researchers, the private sector, and government agencies aimed at solving operational and practical regional ________ problems with a strong connection to the end users. Outcomes from a testbed are more effective observing systems, better use of data in forecasts, improved services, products, and economic/public safety benefits. Testbeds accelerate the translation of R&D findings into better operations, services, and decision-making. A successful testbed requires physical assets as well as substantial commitments and partnerships.
Dabberdt, Walter F., and Coauthors, 2005: Multifunctional Mesoscale Observing Networks. Bull. Amer. Meteor. Soc., 86, 961-982, doi:10.1175/BAMS-86-7-961.