Acccording to the ISO:

A standard is a document that provides requirements, specifications, guidelines or characteristics that can be used consistently to ensure that materials, products, processes and services are fit for their purpose.

According to GB/T 20000.1-2002 Standardization Working Guide Part 1: general terms of standardization and related activities:
A standard is a normative document that is developed upon negotiated consensus, approved by recognized authority, commonly and repeatedly used so as to achieve the best order within a given scope.

Standardization or standardisation is the process of developing and implementing technical standards.