IPA: /təˈrɪfɪkli/
KK: /tɛˈrɪfɪkli/
In a way that is extremely good or impressive.
The movie was terrifically entertaining and kept everyone on the edge of their seats.
Terrifically → It is formed from "terrific" (from Latin *terrificus*, meaning causing terror or fear) and the suffix "-ly" (meaning in a manner of). The word "terrifically" means in a manner that causes terror or is extremely impressive.
Think of something that is 'causing fear' ('terrific') and how it is done 'in a manner' ('-ly'). This helps you remember that 'terrifically' describes something done in an impressive or fear-inducing way.