Statement that translates or expresses a need and its associated constraints and conditions.
Source(s):
NIST SP 800-160v1r1
from
ISO/IEC/IEEE 29148:2018
A condition or capability that must be met or possessed by a system or system element to satisfy an agreement, standard, specification, or other formally imposed documents.
Source(s):
NIST SP 800-160v1r1
from
IEEE Std. 730-2014
A phase of the Development Process wherein the top level definition of the functionality of the system is produced.
Source(s):
NISTIR 5153
under Requirements