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un·der·stand (ŭndər-stănd)
v. un·der·stood (-std), un·der·stand·ing, un·der·stands
a. To become aware of the nature and significance of; know or comprehend: She understands the difficulty involved.
b. To become aware of the intended meaning of (a person or remark, for example): We understand what they're saying; we just disagree with it. When he began describing his eccentric theories, we could no longer understand him.
c. To know and be tolerant or sympathetic toward: hoped that they would understand my complaint.
2. To know thoroughly by close contact or long experience with: That teacher understands children. I understand the basics of car repair.
a. To learn indirectly or infer, as from hearsay: I understand his departure was unexpected. Am I to understand you are staying the night?
b. To assume to be or accept as agreed: It is understood that the fee will be $50.
4. To supply or add (words or a meaning, for example) mentally: A verb is understood at the end of the statement "Yes, let's."
a. To have understanding, knowledge, or comprehension.
b. To have sympathy or tolerance: You're upset. I understand.
2. To learn something indirectly or secondhand; gather.

[Middle English understanden, from Old English understandan : under-, under- + standan, to stand; see stā- in the Appendix of Indo-European roots.]

Synonyms: understand, comprehend, apprehend, grasp
These verbs denote perception of the nature and significance of something. Understand is the most general and can apply to a range of situations or degrees of perception: understood the directions; understands only a little spoken Spanish; couldn't understand what I did wrong.
It can also refer to the thorough knowledge gained by close experience: "No one who has not had the responsibility can really understand what it is like to be President" (Harry S. Truman).
Comprehend stresses wide or thorough perception: "To comprehend is to know a thing as well as that thing can be known" (John Donne).
Apprehend denotes both mental and intuitive awareness: "Intelligence is quickness to apprehend" (Alfred North Whitehead).
To grasp is to seize an idea firmly: "We have grasped the mystery of the atom and rejected the Sermon on the Mount" (Omar N. Bradley).

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. 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:

    Indo-European Roots

    Semitic Roots

    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.