v. pre·vent·ed, pre·vent·ing, pre·vents
1. To keep from happening; avert: took steps to prevent the strike.
2. To keep (a person or thing) from doing something; impede: prevented us from winning; prevented the disease from spreading.
a. To anticipate or counter in advance.
b. To come before; precede.
To present an obstacle: There will be a picnic if nothing prevents.
[Middle English preventen, to anticipate, from Latin praevenīre, praevent- : prae-, pre- + venīre, to come; see gwā- in the Appendix of Indo-European roots.]
pre·vent′a·bili·ty, pre·vent′i·bili·ty n.
pre·venta·ble, pre·venti·ble adj.
Synonyms: prevent, preclude, avert, obviate, forestall
These verbs mean to stop or hinder something from happening, especially by advance planning or action. Prevent implies anticipatory counteraction: "Some contemporaries believed that capitalism and the rise of an international economy would prevent war among 'civilized' states" (John Howard Morrow).
To preclude is to exclude the possibility of an event or action: "a tranquillity which ... his wife's presence would have precluded" (John Henry Newman).
Avert and obviate imply that something, such as a difficulty or necessity, has been removed or avoided: The pilot's quick thinking averted an accident. The short duration of the journey obviated the need for large food supplies. Forestall usually suggests anticipatory measures taken to counteract, neutralize, or nullify the effects of something: We installed an alarm system to forestall break-ins.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.