| a2 |
used to introduce one particular thing or person of a group or kind, but one which is not considered known to the listener. [1/3 definitions] |
| 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. |
| aircraft carrier |
a very large ship with a flat deck on which airplanes can take off and land. |
| album |
a book with blank pages or empty pockets in which a collection can be placed. An album can hold photographs, stamps, or mementos. [1/2 definitions] |
| alert |
a warning of possible danger or the time during which such a warning lasts. [1/3 definitions] |
| algebra |
a form of mathematics used to solve problems in which some of the numbers are not known. In an algebra problem, letters stand for the unknown numbers. |
| alimentary canal |
the tube in the body through which food travels as it is digested. The alimentary canal goes from the mouth to the anus, and includes the esophagus, the stomach, and the small and large intestines. |
| allergy |
a condition in which a person's body has an unusual reaction to certain things. An allergy can cause itching, coughing, sneezing, or trouble breathing. Allergies to animal hair, pollen, and certain foods are among the most common. |
| a.m. |
abbreviation of "ante meridiem," which means "before noon" in Latin; the time between midnight and noon. |
| ambush |
a hiding place from which a surprise attack is made. [1/3 definitions] |
| American Revolution |
the war of 1775-83 in which the American colonies won their independence from Great Britain. |
| anniversary |
the date each year that is the same date on which a wedding or other important event happened. [1/2 definitions] |
| anvil |
a heavy metal block with a flat top on which heated metal objects are hammered into shapes. |
| any |
one or some, no matter which or how many. [1/5 definitions] |
| apartment building |
a building in which there are a number of individual apartments. |
| ape |
a mammal in the group of primates, which includes chimpanzees, gibbons, gorillas, and orangutans. Apes do not have tails. They have very flexible hands and feet. Apes range in size from three to six feet tall, and they can weigh up to 450 pounds. Apes live in the forests in Africa and Asia. [1/2 definitions] |
| appearance |
the way in which someone is dressed or groomed. [1/4 definitions] |
| apple |
the tree on which this fruit grows. [1/2 definitions] |
| aquarium |
a tank or other container filled with water in which water animals and plants are kept. [1/2 definitions] |
| Aquarius |
the eleventh sign of the zodiac, the Water Bearer, which the sun enters about January 21. [1/3 definitions] |
| aquifer |
a layer of rock, sand, or gravel that contains water from which wells and springs are supplied. |