deter

 
Pronunciation: /dɪˈtəː/

verb (deters, deterring, deterred)

[with object]
  • discourage (someone) from doing something by instilling doubt or fear of the consequences: only a health problem would deter him from seeking re-election
  • prevent the occurrence of: strategists think not only about how to deter war, but about how war might occur

Origin:

mid 16th century: from Latin deterrere, from de- 'away from' + terrere 'frighten'

Spelling rule

If a verb ends with a single vowel plus a consonant, and the stress is at the end of the word (as in refer), double the last letter when adding endings which begin with a vowel: (deters, deterring, deterred).