What is feminie of giant?

Answer 1

It is giantess.

Answer 2

In English there are no masculine or feminine forms. English uses gender specific nouns for male or female.

The noun 'giant' is a common gender noun, a word for a male, a female, or an inanimate thing.

When referring to humans, the word giant can be male or female, or the noun giantess is sometimes used for a female.