to perceive the meaning of; grasp the idea of; comprehend: to understand Spanish; I didn't understand your question.
2.
to be thoroughly familiar with; apprehend clearly the character, nature, or subtleties of: to understand a trade.
3.
to assign a meaning to; interpret: He understood her suggestion as a complaint.
4.
to grasp the significance, implications, or importance of: He does not understand responsibility.
5.
to regard as firmly communicated; take as agreed or settled: I understand that you will repay this loan in 30 days.
6.
to learn or hear: I understand that you are going out of town.
7.
to accept as true; believe: I understand that you are trying to be truthful, but you are wrong.
8.
to construe in a particular way: You are to understand the phrase literally.
9.
to supply mentally (something that is not expressed).
–verb (used without object)
10.
to perceive what is meant; grasp the information conveyed: She told them about it in simple words, hoping they would understand.
11.
to accept tolerantly or sympathetically: If you can't do it, I'll understand.
12.
to have knowledge or background, as on a particular subject: He understands about boats.
13.
to have a systematic interpretation or rationale, as in a field or area of knowledge: He can repeat every rule in the book, but he just doesn't understand.
Origin: bef. 900; ME understanden, understonden, OE understondan; c. D onderstaan.See under-, stand
[uhn-der-stand] 
verb, -stood, -stand⋅ing.
dərˈstænd