| abiogenesis |
the production of living organisms from nonliving matter; spontaneous generation. |
| abiotic |
characterized by an absence of living organisms; without life. |
| acquired characteristic |
a change in the structure or function of a living organism that is caused by environmental factors and may not be transmitted genetically. |
| adaptation |
a particular change in the body of a living thing that helps the animal or plant to survive under new conditions. An adaptation happens over a very long time. [2/4 definitions] |
| ADP |
a biochemical compound involved in the storing and releasing of energy in all living cells; adenosine diphosphate. (Cf. ATP.) |
| aerobic |
occurring or living only in the presence of oxygen. [1/3 definitions] |
| ahimsa |
(Sanskrit) the principle of nonviolence based on the belief in the sacredness of all living creatures, as held by Buddhists, Hindus, and others. |
| air chamber |
a compartment in which air is confined for a special use, as in a pump, a hydraulic fluid regulator, or a living organism. |
| air mattress |
a mattress filled with air, used esp. for camping, mobile living, or as an extra bed for visitors. |
| air sac |
an air-filled space or cavity in a living organism, esp. any of the ends of certain bronchial tubes in a bird's body that connect with the larger body cavity and assist in breathing. |
| ala |
a wing or winglike part or structure on a living organism. |
| Algonquin |
any of several Algonquian Indian tribes formerly living in the region of southern Canada and the St. Lawrence River, or a member of one of these tribes. [1/3 definitions] |
| alien |
a living being from another planet; extraterrestrial. There is no evidence that aliens exist, but many people believe there is life on other planets. [1/5 definitions] |
| alive |
having life; living. [2/3 definitions] |
| allogenic |
caused by environmental factors that do not involve living organisms. [1/2 definitions] |
| allopatric |
living in different geographic areas or in isolation, used esp. in reference to closely related species or to different populations of a single species. [1/2 definitions] |
| Alpine |
(l.c.) of, like, living in, or characteristic of high mountains or mountain regions above the timberline. [2/4 definitions] |
| Amish |
a Christian sect that separated from the Mennonites in the seventeenth century, the members of which advocate simple living and now live mostly in farming areas of the northeastern United States. [1/3 definitions] |
| amoeba |
a tiny living thing made of only one cell. Amoebas move by changing their shape. They eat by wrapping their bodies around their food. Amoebas live in fresh and salt water, soil, and in animals. Most kinds of amoebas can only be seen through a microscope. |
| anabolism |
the process in living organisms by which complex structures are synthesized from simple ones, as body tissues from food. |
| anaerobe |
any of various microorganisms, such as certain bacteria, that are capable of living without air or oxygen. |