| 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] |
| alga |
"Alga" is the singular form of the word "algae." Algae are living things that live mainly in water and make their food by using light from the sun. Algae are similar to plants, but they are not usually considered to be plants because they are different in some ways. For example, algae don't have roots and leaves like plants do. Most forms of algae are very helpful for animals and people. Seaweed is a kind of algae, which many people eat and can also be used in making other things. Fish and other water animals use algae for food. |
| algae |
Algae are living things that live mainly in water and make their food by using light from the sun. Algae are similar to plants, but they are not usually considered to be plants because they are different in some ways. For example, algae don't have roots and leaves like plants do. Most forms of algae are very helpful for animals and people. Seaweed is a kind of algae, which many people eat and can also be used in making other things. Fish and other water animals use algae for food. "Algae" is a plural word. The singular form is "alga." |
| 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. |
| angle1 |
An angle is the direction from which you see something, or the particular way you think about something. [1/4 definitions] |
| 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] |
| anything |
If you like doing anything with your friends, it means that you like whatever you do with your friends. It doesn't matter which thing you do--you're always happy. If your brother will eat anything, it means he doesn't care what he eats. Maybe he will even eat bugs! [1/3 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] |