What is a ‘cusp’?

Reading time: Less than 1 minute

Increase your vocabulary and you’ll make your writing much more precise. That’s why I provide a word of the week. Today’s word: cusp….

I was reading an interview with fiction writer Emma Richler (pictured above) this week when I stumbled across the word cusp. Here is how she used it (in answering a question about which historical period she wished she’d lived through):

I find the late Regency…a period of enduring fascination…This was a time, it seems to me of incipient and flourishing change, a period on the cusp of a monumental change and clamour, which was the Victorian era.

Of course I already knew the standard definition of a cusp, referring to an edge or a turning point, familiar from such expressions as ‘the cusp of fame.’ As well, I also understood that it referred not only to the point on the grinding surface of a tooth but also to the imaginary line that separates a pair of consecutive signs in the zodiac.

I didn’t know cusp could also refer to  either horn of a crescent moon OR  a fixed point on a mathematical curve at which a point tracing the curve would exactly reverse its direction of motion.

And I knew nothing about the etymology of the word. It turns out that the noun is Latin, from the word cuspis, meaning “point, spear, pointed end, head.” Interestingly, the astrological use of the term is the earliest.