component

This term is defined in ECSS-E-ST-10-12C as
device that performs a function and consists of one or more elements joined together and which cannot be disassembled without destruction

This term is defined in ECSS-E-ST-35C Rev. 1 as
smallest individual functional unit considered in a subsystem

This term is defined in ECSS-E-ST-33-01C as
assembly or any combination of parts, subassemblies and assemblies, and assemblies mounted together and normally capable of independent operation in a variety of situations

This term is defined in ECSS-Q-ST-70-08C as
device which performs an electronic, electrical or electromechanical function and consists of one or more elements joined together and which cannot normally be disassembled without destruction

This term is defined in ECSS-S-ST-00-01C as
set of materials, assembled according to defined and controlled processes, which cannot be disassembled without destroying its capability and which performs a simple function that can be evaluated against expected performance requirements