1. (noun)understanding, apprehension, discernment, savvy the cognitive condition of someone who understands
"he has virtually no understanding of social cause and effect"
2. (noun)agreement, understanding the statement (oral or written) of an exchange of promises
"they had an agreement that they would not interfere in each other's business"; "there was an understanding between management and the workers"
3. (noun)sympathy, understanding an inclination to support or be loyal to or to agree with an opinion "his sympathies were always with the underdog"; "I knew I could count on his understanding"
4. (noun)reason, understanding, intellect the capacity for rationalthought or inference or discrimination "we are told that man is endowed with reason and capable of distinguishing good from evil"