| abacus |
a device used to make arithmetic calculations, consisting of a frame with parallel rods or grooves that hold movable counters such as beads. |
| abomasum |
the fourth stomach chamber of cud-chewing mammals such as cows, in which food is digested. |
| abracadabra |
a nonsense word thought to produce a magical effect such as the warding off of disaster or disease. [1/2 definitions] |
| absenteeism |
habitual or repeated absence from a place where regular attendance is required, such as work or school. |
| acacia |
any of several ornamental trees related to the acacia, such as the locust. [1/2 definitions] |
| academician |
one who belongs to an organization, such as an academy, that promotes learning. [1/2 definitions] |
| accelerant |
a substance capable of accelerating a process, such as the spreading of a fire. |
| account executive |
in a company such as an advertising agency, a person responsible for managing one or more clients' accounts and often for securing new accounts. |
| acid rain |
rain that has high acidity because of being mixed with pollutants such as vehicle exhausts and residues from burning of fossil fuels for energy or from chemical manufacturing. |
| acinus |
one of the small divisions in an aggregate fruit such as a blackberry. [1/2 definitions] |
| acquirement |
something acquired, such as knowledge or skill. [1/2 definitions] |
| acrogen |
a plant that produces no flower and grows only from the tip of the stem, such as a fern or moss. |
| actinic rays |
electromagnetic radiation, such as x-rays or ultraviolet light, that can produce an image on a photographic emulsion. |
| active |
in grammar, designating the voice or form of a verb whose subject acts through the verb, rather than being the object of the verb's action, such as "signed" in "Five petitioners signed the document". (Cf. passive.) [1/7 definitions] |
| act of God |
in law, a sudden unforeseen event, esp. a natural disaster such as an earthquake, flood, or tornado, that is caused entirely by forces of nature and could not have been prevented. |
| addict |
one who depends on or craves a habit-forming substance, such as a drug. [2/4 definitions] |
| adduct |
to move or pull (a body part such as a muscle) toward the main axis. (Cf. abduct.) |
| adenine |
in chemistry, a crystalline base that is a constituent of nucleic acid in organs such as the pancreas and spleen. |
| adhesive |
an adhesive substance or material such as glue. [1/2 definitions] |
| adiabatic |
of, relating to, or denoting a process that occurs without loss or gain of heat, such as a change in the volume or pressure of the contents of a container. |
| adversative |
an adversative word or phrase, such as "but" or "on the contrary". [1/2 definitions] |