subassembly

[suhb-uh-sem-blee] /ˌsʌb əˈsɛm bli/
noun, plural subassemblies.
1.
a structural assembly, as of electronic or machine parts, forming part of a larger assembly.
Origin
1925-30; sub- + assembly
British Dictionary definitions for subassembly

subassembly

/ˌsʌbəˈsɛmblɪ/
noun (pl) -blies
1.
a number of machine components integrated into a unit forming part of a larger assembly