tr.v. mit·i·gat·ed, mit·i·gat·ing, mit·i·gatesPhrasal Verb:
1. To make less severe or intense; moderate or alleviate. See Synonyms at relieve.
2. To make alterations to (land) to make it less polluted or more hospitable to wildlife.
mitigate against Usage Problem
1. To take measures to moderate or alleviate (something).
2. To be a strong factor against (someone or something); hinder or prevent.
[Middle English mitigaten, from Latin mītigāre, mītigāt- : mītis, soft + agere, to drive, do; see ACT.]
miti·ga·ble (-gə-bəl) adj.
miti·ga′tive, miti·ga·to′ry (-gə-tôr′ē) adj.
Usage Note: Mitigate, meaning "to make less severe, alleviate" is sometimes used where militate, which means "to cause a change," might be expected. The confusion arises when the subject of mitigate is an impersonal factor or influence, and the verb is followed by the preposition against, so the meaning of the phrase is something like "to be a powerful factor against" or "to hinder or prevent," as in His relative youth might mitigate against him in a national election. Some 70 percent of the Usage Panel rejected this usage of mitigate against in our 2009 survey. Some 56 percent also rejected the intransitive use of mitigate meaning "to take action to alleviate something undesirable," in What steps can the town take to mitigate against damage from coastal storms? Perhaps the use with against in the one instance has soured Panelists on its use in the other. This intransitive use is relatively recent in comparison with the long-established transitive use, so novelty might play a role as well.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 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.