'equal' originates from Latin, specifically the word 'aequalis', where 'aequus' meant 'even' or 'level'; 'gamete' originates from New Latin/Greek, specifically the word 'gamētēs', where 'gamos' meant 'marriage' or 'union'.

'equal-gamete' is a modern compound formed from the adjective 'equal' (from Latin via Old French) and the biological term 'gamete' (coined in New Latin from Greek); the compound arose in scientific usage to describe gametes of similar size and form, paralleling the term 'isogamete'.

Initially, the roots meant 'even/level' and 'marriage/union' respectively, but together they evolved to mean 'a gamete of similar size/form' in modern biology.