sub- /sʌb/ BrE AmE prefix
[ Language: Latin ; Origin: sub 'under, close to' ]
1 . under or below a particular level or thing:
sub-zero temperatures
subsoil (=beneath the surface)
2 . less important or powerful than someone or something, or of lower rank than someone:
a sublieutenant
3 . part of a bigger whole:
a subsection
a subcommittee
4 . not as good as other people or things:
substandard housing
subnormal intelligence
5 . technical almost:
subtropical heat