Question

why do metallic oxide are called basic oxide​

Answer 1

metallic oxides are called basic oxides because when these oxides react with water they form bases.

Answer 2

they are called basic oxide because they react with dilute acids to form salt and water ..and they also react with water to form metal hydroxides which are alkaline in nature . as those metal oxides releases (-OH) ions in solutions..

so metallic oxides also basic oxides...