'apoapside' originates from New Latin/Modern scientific usage, specifically from 'apoapsis', where 'apo-' meant 'away from' and 'apsis' meant 'arch' or 'loop' (used for the extreme points of an orbit).

'apoapside' changed from Neo-Latin and Greek elements: Greek 'apó' + 'ápsis' (ἀπό + ἄψις) produced Neo-Latin 'apoapsis', and English later adopted the variant spelling 'apoapside' as an alternative form to 'apoapsis'.

Initially, the combined elements meant 'a farthest point (arch or loop) away from' and this developed into the technical astronomical meaning 'the farthest point in an orbit'; the meaning has remained essentially the same, with 'apoapside' functioning as a less common or archaic variant of 'apoapsis'.