It's Merriam-Webster's Word of the Day for September 26th.
Today's word is deter, also pronounced deter and spelled D-E-T-E-R.
Deter is a verb.
To deter someone is to discourage or prevent them from acting.
To deter a thing is to stop or limit it.
Here's the word used in a sentence from Becoming Earth, How Our Planet Came to Life by Ferris Yaber.
Sergei and other scientists have proposed that rather than rely on robust and elaborate defenses,
certain grasses negotiated a symbiosis, an ecological partnership with large herbivores.
These grasses offered grazers endless fields of tender green leaves that quickly regenerated when shorn.
In exchange for this perpetual sustenance,
mammoths and other megafauna trampled eight and otherwise deterred the grasses' main competitors,
such as shrubs and trees, and fertilized the fields with their copious dung.
The word deter is rooted in fear.
It was borrowed into English around the mid-16th century from the Latin verb de terere,
which in turn was formed by combining de, meaning from, or away, with terere, meaning to frighten.
Terere is also the source of the words terror, terrible,
and even terrific, which originally meant very bad or frightful.
These days,
you may be deterred by something that frightens you or by something that simply causes you to think about the difficult or unpleasant consequences of continuing.
Things as well as people can be deterred.