| Term | Definition |
| acetic | (adj.) of or like vinegar or ___ acid. : her humor was quite ___. |
| Achillean | (adj.) Invincible except to one single vulnerability |
| achromatic | (adj.) without color : ___ gloom. |
| acid | (n.) a chemical substance that neutralizes alkalis, dissolves some metals, and turns litmus red; typically, a corrosive or sour-tasting liquid of this kind : rainwater is a very weak ___ |
| acknowledgment | (n.) acceptance of the truth or existence of something : there was no ___ of the family's trauma. |
| acme | (n.) the point at which someone or something is best, perfect, or most successful : physics is the ___ of scientific knowledge. |
| acoustic | (adj.) relating to sound or the sense of hearing : dogs have a much greater ___ range than humans. |
| acquaint | (v.) make someone aware of or familiar with : new staff should be ___ed with fire exit routes |
| acquiesce | (v.) accept something reluctantly but without protest : Victoria ___ in his decision. |
| acquit | (v.) free (someone) from a criminal charge by a verdict of not guilty : she was ___ed on all counts |
| acreage | (n.) an area of land, typicially when used for agricultural purposes, but not necessarily measured in acres : a 35% increase in net ___. |
| acrid | (adj.) having an irritatingly strong and unpleasant taste or smell : ___ fumes. • angry and bitter : an ___ farewell. |
| acrimonious | (adj.) (typically of speech or a debate) angry and bitter : an ___ dispute about wages. |
| actuary | (n.) someone versed in the collection and interpretation of numerical data (especially someone who uses statistics to calculate insurance premiums |
| actuate | (v.) cause (a machine or device) to operate : the pendulum ___s an electrical switch. |
| acumen | the ability to make good judgments and quick decisions, typically in a particular domain : business ___. |
| acute | (adj.) (of a bad, difficult, or unwelcome situation or phenomenon) present or experienced to a severe or intense degree : an ___ housing shortage | the problem is ___ and getting worse. |
| addle | (v.) make unable to think clearly; confuse : being in love must have ___ed your brain |
| adherent | (n.) someone who supports a particular party, person, or set of ideas : he was a strong ____ of monetarism. |
| adjacent | (adj.) next to or adjoining something else : ___ rooms | the area ___ to the fire station. |
| adjudge | (v.) consider or declare to be true or the case : she was ___d guilt |
| adjunct | (n.) a thing added to something else as a supplementary rather than an essential part : computer technology is an ___ to learning. |
| adjure | (v.) urge or request (someone) solemnly or earnestly to do something : I ___ you to tell me the truth. |
| adjutant | (n.) a military officer who acts as an administrative assistant to a senior officer. |
| admissible | (adj.) acceptable or valid, esp. as evidence in a court of law : the Court unanimously held that the hearsay was ___ |