| act up |
to happen again or return, as an illness or malfunction. [1/2 definitions] |
| acute |
an angle of less than ninety degrees. [1/4 definitions] |
| acute angle |
an angle of less than ninety degrees. |
| A.D. |
after the birth of Jesus Christ. A.D. is an abbreviation for anno domini, which means "in the year of the Lord" in Latin. Something that happened in A.D. 50 happened fifty years after the birth of Christ. |
| adage |
an old familiar saying that shows the wisdom of a group of people; proverb. |
| adaptation |
the result of such an act or process. [2/4 definitions] |
| adjective |
a word that describes a noun or pronoun. In the sentence, "It was a hard test," the word "hard" is an adjective. It describes the noun "test." |
| admiral |
an officer in the United States Navy of the highest rank; the commander of a fleet of ships or military unit. |
| adolescent |
having to do with the period when a person is changing from a child to an adult. [2 definitions] |
| adopt |
to become a parent of (a child) by law, or to accept an animal as a pet and become responsible for it. [1/3 definitions] |
| adult |
an animal or plant that is fully grown and mature. [1/4 definitions] |
| advanced |
beyond an early or beginning level, or beyond the level of others; in a very developed state. [1/2 definitions] |
| advice |
an idea or opinion offered as help in making a choice or a decision. |
| affair |
an event, matter, or happening. [1/5 definitions] |
| African American |
an American who has ancestors of African descent. |
| after all |
used to remind the listener of an important fact or to ask the listener to consider this fact. [1/2 definitions] |
| agency |
a company or organization that does business in support of other companies or people. An agency helps people do things that are difficult or complicated to do just by themselves. [2/3 definitions] |
| aggression |
an attack or war against a country started without good cause by another country. [1/2 definitions] |
| agree |
to come to an understanding or a shared decision. [1/5 definitions] |
| agreement |
an understanding between people or groups that states what kind of action is to be taken and what each person's responsibility will be. The document that describes this understanding is also called an agreement. [1/4 definitions] |
| air conditioner |
a machine that cools the air in a room or car. An air conditioner also takes the dust and dampness out of the air. |