The term 'prefix with SPHERE' refers to a set of eight words that all begin with the prefix 'SPHERE' and end with a different suffix. The words are hemi (4 letters), atmo (4 letters), iono (4 letters), exo (3 letters), eco (3 letters), tropo (5 letters), uni (3 letters), and strat (6 letters). Hemi is a prefix meaning 'HALF, ' atmo is a prefix meaning 'ATMOSPHERE, ' iono is a prefix meaning 'ionosphere, ' exo is a prefix meaning 'OUTSIDE, ' eco is a prefix meaning 'ecosphere, ' tropo is a prefix meaning 'troposphere, ' uni is a prefix meaning 'UNIVERSE, ' and strat is a prefix meaning 'stratosphere.' Together, these words form a set of terms that refer to different layers of the Earth's ATMOSPHERE.