'narrow-band' originates from the combination of 'narrow' and 'band', where 'narrow' meant 'limited in extent' and 'band' referred to 'a range of frequencies'.

'narrow-band' evolved from the concept of 'narrow' and 'band' being used together in telecommunications to describe limited frequency ranges.

Initially, it meant 'a limited range of frequencies', and this meaning has largely remained the same in modern usage.