Definition
To deter is to stop an action before it starts — not by force, but by making the cost look too high. The Latin deterrere means 'to frighten off'. High walls, harsh penalties, and a single cautionary tale all deter; what they have in common is that they work on the mind, not the body. A deterrent succeeds only if it is believed: what deters does not push you away so much as quietly persuade you not to come.
Examples
- Steep fines are meant to deter drivers from speeding.
- The harsh climb did not deter them; if anything it seemed to galvanize the group.
- A few bad experiences were enough to deter her from investing again.
Collocations
deter crime·act as a deterrent·deter would-be offenders·do little to deter
Synonyms
discourage·dissuade·impede·inhibit·put off
Antonyms
encourage·galvanize·motivate
Word family
deterrent (noun)·deterrence (noun)
In TOEFL & IELTS
Frequent in IELTS Writing Task 2 on crime and policy — 'harsher penalties deter offenders' is a ready-made argument, and 'a deterrent' is the noun you want. TOEFL passages use it for animal defenses and strategy ('nuclear deterrence'). Watch the preposition: deter someone *from* doing something. Don't confuse it with 'detain' or 'deteriorate'.