mid-15c., "impartial treatment;" 1610s, "equal ranking;" from Latin aequiparationem (nominative aequiparatio) "an equalizing, comparison," from past participle stem of aequiparare "put on equality, compare," from aequipar "equal, alike," from aequus "equal, even" (see equal, adj.) + par (see par, n.). Related: Equiparate.