understand

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To perceive and comprehend the nature and significance of; grasp. See Synonyms at apprehend.
2. v. To know thoroughly by close contact or long experience with: That teacher understands children.
3. v. To grasp or comprehend the meaning intended or expressed by (another): They have trouble with English, but I can understand them.
4. v. To comprehend the language, sounds, form, or symbols of.
5. v. To know and be tolerant or sympathetic toward: I can understand your point of view even though I disagree with it.
6. v. To learn indirectly, as by hearsay: I understand his departure was unexpected.
7. v. To infer: Am I to understand you are staying the night?
8. v. To accept (something) as an agreed fact: It is understood that the fee will be 50 dollars.
9. v. To supply or add (words or a meaning, for example) mentally.
10. v. To have understanding, knowledge, or comprehension.
11. v. To have sympathy or tolerance.
12. v. To learn something indirectly or secondhand; gather.

Century Dictionary and Cyclopedia

1. To receive from a word or collocation of words or from a sign the idea it is intended to convey: with the thing said, the person speaking, or the language as the direct object of the verb.
2. To interpret the signification of; seize the idea of; comprehend as resulting from a thought, principle, or rule; explain.
3. To receive information about; learn by paying heed to what is said and done; consider.
4. To know in substance, as a fact or saying; be acquainted with; recognize.
5. To take as meant or implied; imply; infer; assume; take for granted: chiefly in the past participle.
6. To recognize as implied or meant, although not expressed; supply mentally, as a word necessary to bring out the sense of an author: as, in the phrase ‘All are mortal,’ we must understand the word men, living beings, or the like.
7. To stand under.
8. To have the use of the intellectual faculties; be an intelligent and conscious being; have understanding; be wise.
9. To be informed by another; learn.
10. To give attention; listen.

Wiktionary

1. v. To be aware of the meaning of.
2. v. To believe, based on information.
3. v. To impute meaning, character etc. that is not explicitly stated.
4. v. To apply values (axioms).

GNU Webster's 1913

1. v. To have just and adequate ideas of; to apprehended the meaning or intention of; to have knowledge of; to comprehend; to know
2. v. To be apprised, or have information, of; to learn; to be informed of; to hear.
3. v. To recognize or hold as being or signifying; to suppose to mean; to interpret; to explain.
4. v. To mean without expressing; to imply tacitly; to take for granted; to assume.
5. v. To stand under; to support.
6. v. To have the use of the intellectual faculties; to be an intelligent being.
7. v. To be informed; to have or receive knowledge.

WordNet 3.0

1. v. know and comprehend the nature or meaning of
2. v. be understanding of
3. v. perceive (an idea or situation) mentally
4. v. make sense of a language
5. v. believe to be the case