2 ADJ If someone is apt to do something, they often do it and so it is likely that they will do it again. □ She was apt to raise her voice and wave her hands about.
ap|ti|tude /æ pt I tjuːd, [AM ] -tuːd/ (aptitudes ) N‑VAR Someone's aptitude for a particular kind of work or activity is their ability to learn it quickly and to do it well. □ [+ for ] An aptitude for computing is beneficial for students taking this degree.
a p|ti|tude test (aptitude tests ) N‑COUNT An aptitude test is a test that is specially designed to find out how easily and how well you can do something.
aqua /æ kwə/ COLOUR Aqua is the same as the colour aquamarine . □ …floor-length curtains in restful aqua and lavender colours.
aqua|marine /æ kwəməriː n/ (aquamarines )
1 N‑VAR Aquamarines are clear, greenish-blue stones, sometimes used to make jewellery. □ A necklace set with aquamarines. □ …a large aquamarine ring.
2 COLOUR Aquamarine is used to describe things that are greenish-blue in colour. □ …warm aquamarine seas and white beaches.
aquar|ium /əkweə riəm/ (aquariums or aquaria /əkweə riə/)
1 N‑COUNT An aquarium is a building, often in a zoo, where fish and underwater animals are kept.
2 N‑COUNT An aquarium is a glass tank filled with water, in which people keep fish.
Aquar|ius /əkweə riəs/
1 N‑UNCOUNT Aquarius is one of the twelve signs of the zodiac. Its symbol is a person pouring water. People who are born approximately between 20th January and 18th February come under this sign.
2 N‑SING An Aquarius is a person whose sign of the zodiac is Aquarius.
aquat|ic /əkwæ t I k/
1 ADJ [usu ADJ n] An aquatic animal or plant lives or grows on or in water. □ …aquatic birds.
2 ADJ Aquatic means relating to water. □ …aquatic consultant Ben Tucker. □ …our aquatic resources.
aque|duct /æ kw I dʌkt/ (aqueducts )
1 N‑COUNT An aqueduct is a long bridge with many arches, which carries a water supply or a canal over a valley. □ …an old Roman aqueduct.
2 N‑COUNT An aqueduct is a large pipe or canal which carries a water supply to a city or a farming area. □ …a nationwide system of aqueducts to carry water to the arid parts of this country.
aque|ous /e I kwiəs/ ADJ [ADJ n] In chemistry, an aqueous solution or cream has water as its base. [TECHNICAL ] □ …an aqueous solution containing various sodium salts.
aqui|fer /æ kw I fə r / (aquifers ) N‑COUNT In geology, an aquifer is an area of rock underneath the surface of the earth which absorbs and holds water. [TECHNICAL ]
aqui|line /æ kw I la I n/ ADJ [usu ADJ n] If someone has an aquiline nose or profile, their nose is large, thin, and usually curved. [FORMAL ] □ He had a thin aquiline nose.
Arab /æ rəb/ (Arabs )
1 N‑COUNT Arabs are people who speak Arabic and who come from the Middle East and parts of North Africa.
2 ADJ [usu ADJ n] Arab means belonging or relating to Arabs or to their countries or customs. □ The Arab world is particularly keen on the use of cardamom with tea.
ara|besque /æ rəbe sk/ (arabesques ) N‑COUNT An arabesque is a position in ballet dancing. The dancer stands on one leg with their other leg lifted and stretched out backwards, and their arms stretched out in front of them.
Ara|bian /əre I biən/ ADJ Arabian means belonging or relating to Arabia, especially to Saudi Arabia. □ …the Arabian Peninsula.
Ara|bic /æ rəb I k/
1 N‑UNCOUNT Arabic is a language that is spoken in the Middle East and in parts of North Africa.
2 ADJ Something that is Arabic belongs or relates to the language, writing, or culture of the Arabs. □ …the development of modern Arabic literature. □ …Arabic music.
3 ADJ [ADJ n] An Arabic numeral is one of the written figures such as 1, 2, 3, or 4.
Ar|ab|ist /æ rəb I st/ (Arabists ) N‑COUNT An Arabist is a person who supports Arab interests or knows a lot about the Arabic language.
ar|able /æ rəb ə l/ ADJ [usu ADJ n] Arable farming involves growing crops such as wheat and barley rather than keeping animals or growing fruit and vegetables. Arable land is land that is used for arable farming.
Arab Spring N‑PROPER The Arab Spring is a period of time in and around 2011 to 2012 during which people in the Middle East and Africa tried to achieve democratic reforms. □ Social networking sites played an important role in the events of the Arab Spring.
ar|bi|ter /ɑː r b I tə r / (arbiters )
1 N‑COUNT An arbiter is a person or institution that judges and settles a quarrel between two other people or groups. [FORMAL ] □ He was the ultimate arbiter on both theological and political matters.
2 N‑COUNT An arbiter of taste or style is someone who has a lot of influence in deciding what is fashionable or socially desirable. [FORMAL ]
ar|bi|trage /ɑː r b I trɑːʒ/ N‑UNCOUNT [oft N n] In finance, arbitrage is the activity of buying shares or currency in one financial market and selling it at a profit in another. [BUSINESS ]
ar|bi|tra|ger /ɑː r b I trɑːʒɜː r / (arbitragers ) also arbitrageur N‑COUNT In finance, an arbitrager is someone who buys currencies, securities, or commodities on one country's market in order to make money by immediately selling them at a profit on another country's market. [BUSINESS ]
ar|bi|trary /ɑː r b I tri, [AM ] -treri/ ADJ If you describe an action, rule, or decision as arbitrary , you think that it is not based on any principle, plan, or system. It often seems unfair because of this. [DISAPPROVAL ] □ Arbitrary arrests and detention without trial were common. ● ar|bi|trari|ly /ɑː r b I treə r I li/ ADV [ADV with v] □ The victims were not chosen arbitrarily.