The term cusp is an old one and it was first used in astrology and later in other contexts:

1580s, in astrology, "first entrance of a house in the calculation of a nativity," from Latin cuspis "point, spear, pointed end, head," which is of unknown origin. Astronomical sense is from 1670s, "point or horn of a crescent." Anatomical sense of "a prominence on the crown of a tooth" is from 1839. (Etymonline)

but the metaphorical expression on the cusp of something meaning “be at the time when a situation or state is going to change” became curiously popular only a few decades ago, from the 1990s as shown by Google Books.

enter image description here

While it probably derives from the astrological use of cusp, I wonder what may have caused its popularity which, as shown, has been increasing steadily and consistently in recent years.

  • I never knew there was such a thing as "the astrological use of cusp", but I seriously doubt it's particularly significant in relation to on the cusp of [some significant change]. Not quite so marked, but there's been a significant increase in prevalence of on the verge of in recent decades, too. Some usages go in and out of fashion, is all. Commented Apr 9, 2021 at 18:00
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    @FumbleFingers Born on the Leo/Virgo cusp etc. Either on the last day or on the first day of an astrological sign, supposedly, the lucky earthling shares characterial traits of both signs..
    – Mari-Lou A
    Commented Apr 9, 2021 at 18:04
  • Maybe it's partly just that across the whole of the Anglophone world, more people are being exposed to more different "turns of phrase" than was the case many decades ago. And some of the previously-unfamiliar expressions they encounter are so striking they get repeated more... Commented Apr 9, 2021 at 18:05
  • ...Witness the same thing happening with, for example, rife / ripe with opportunity Commented Apr 9, 2021 at 18:05
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    I think it has to do with being on the cusp of a new millenium, a new century, and being on the cusp of extinction, global warming etc. Just a wild guess.
    – Mari-Lou A
    Commented Apr 9, 2021 at 18:15

1 Answer 1


This ngram compares some apparently unrelated data. The timeline starts at 1960, and ends 2019. It seems to show an increase in many expressions relating to "on the cusp" starting roughly 1995, correspondingly with "Y2K"; and then increasing incrementally with my baseline ("on the way") , even though"Y2K" usage dropped significantly after 2001.

enter image description here

*ngrams started 2010, and only collects data until 2019. Perhaps it is due to a data collection bias.

Also interesting is that "Global Warming" dropped in mention by a significant percentage, even though "end of the world" crept up in usage, and Extinction Level Event never came close in any search...

I think "on the cusp" is just another expression that describes a certain type of morbid foreboding of a future change.

[I have seen past data that suggests that the majority of US citizens in the late 1930s knew there would be another great war in their then near future. But that would be out-of-scope for the question.]

My analysis:

This data indicates a fear of the future, and a reluctance to investigate the science.

  • The decrease in "global warming" coincides with a big increase in "climate change". graph
    – Barmar
    Commented Apr 13, 2021 at 14:18
  • I don't associate "on the cusp" specifically with changes for the worse or foreboding.
    – Barmar
    Commented Apr 13, 2021 at 14:20

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