The process associated with obtaining products or services, typically through contracts involving the expenditure of financial resources, as well as to products or services that may be obtained on a cost-free basis via other mechanisms (e.g., the downloading of public domain software products and other software products with limited or no warranty, such as those commonly known as freeware or shareware from the commercial Internet).
Sources:
CNSSI 4009-2022 from NSA/CSS Policy 3-4 - adapted

  Process of obtaining a system, product, or service.
Sources:
NIST SP 800-160v1r1 from ISO/IEC/IEEE 15288:2015

  A process by which digital evidence is duplicated, copied, or imaged.
Sources:
NIST SP 800-101 Rev. 1 under Acquisition
NIST SP 800-72 under Acquisition

  Includes all stages of the process of acquiring product or services, beginning with the process for determining the need for the product or services and ending with contract completion and closeout.
Sources:
NIST SP 800-161r1-upd1 [11/1/2024 errata update]

  Includes all stages of the process of acquiring product or service, beginning with the process for determining the need for the product or service and ending with contract completion and closeout.
Sources:
NISTIR 7622 under Acquisition