the word terrifically is built upon the adjective terrific, which originates from the latin terrificus, meaning "causing terror". this latin term itself is a compound of terrere, "to frighten", and facere, "to make". while the original sense was literally "terror-inducing", the meaning softened and intensified in english during the 19th century, shifting from "dreadful" to an informal sense of "extraordinarily great". the suffix -ally, a common adverbial ending in english, is appended to form the adverb, indicating the manner or degree of an action. thus, terrifically evolved from a descriptor of fear to a general intensifier meaning "extremely".

Structure: terrific (causing terror) + ally (adverb suffix) terrific: from latin terrificus, from terrere (to frighten) + facere (to make). ally: from latin adverbial suffix -aliter, via old french -alment, meaning "in a manner of".