The words 'terrible' and 'terrific' both trace back to the same root: 'terror.' Centuries ago, both words carried the meaning of inducing terror. But in the early 20th century, 'terrific' took a surprising turn and began to signify something excellent, rather than frightening or terror-inducing.
This shift occurred as 'terrific' slowly evolved. Initially, it meant something terror-inducing, but over time, it came to represent general intensity. You might hear about a 'terrific clamor,' referring to an overwhelming amount of noise, a bit of hyperbole suggesting 'so much noise, it could terrify!' This sense of intensity gradually transformed into a broader notion of something more intense than usual. Words like these, once accepted as intensifiers, were soon applied to positive experiences—'terrific beauty' or 'terrific joy.' This led to the full positive meaning of 'terrific!' A similar change happened with 'tremendous,' which once meant 'fear-inducing,' and even 'formidable,' which in French has evolved to mean 'really great,' though not yet in English. However, in English, 'formidable' now carries a positive connotation of immense talent or ability.
The shift from fear to positive enthusiasm isn't guaranteed. Take 'awful,' which began as a term related to fear, derived from 'awe,' once a word associated with trembling before something powerful. It became an intensifier, such as in the phrase 'that pie was awful good!' But unlike 'terrific,' it never took on a fully positive meaning. However, its sibling, 'awesome,' did make that leap.
The entirely positive meaning of 'awesome,' which emerged in the 1980s, is a relatively recent development. Initially a slang term, it carried a touch of irony or sarcasm. This ingredient of irony appears to be key in these shifts. The positive connotation of 'terrific' also emerged from the slang-rich flapper era, when terms like 'killer' took on playful, positive meanings. Similarly, 'egregious' made a reverse shift, going from meaning 'noteworthy' or 'excellent' to negative, likely due to ironic usage. We also see modern slang words crossing over in this way—'sick,' 'ill,' 'wicked,' and 'bad' now often mean the opposite of their original negative definitions.
Crossover words stand as a remarkable example of our incredible ability to mold language as we communicate. They represent our power to overcome fear, transforming terror into something truly magnificent.