'hemispherical' originates from the Greek word 'hēmisphairion', where 'hēmi-' meant 'half' and 'sphaira' meant 'sphere'.

'hēmisphairion' transformed into the Latin word 'hemisphaerium', and eventually became the modern English word 'hemisphere' through Old French.

Initially, it meant 'half of a sphere', and this meaning has largely remained the same in modern usage.