IPA: /ɡɪˈɡæntɪkli/
KK: /gɪˈgæntɪkli/
In a very large or enormous way.
The elephant moved gigantically through the forest, making the trees sway.
Gigantically → It is formed from "gigantic" (from Latin *giganticus*, meaning enormous or huge) and the suffix "-ly" (meaning in a manner). The word "gigantically" means in a manner that is enormous or huge.
Think of something that is 'enormous' ('gigantic') and how it is done 'in a manner' ('-ly'). This helps you remember that 'gigantically' describes something done in an enormous way.