atmosphere
2 the space around things or above the ground • The balloons floated up into the air.
3 used to refer to travel in aircraft • My uncle often travels by air.
air conditioning
NOUN a way of keeping cool, fresh air in a building
aircraft
NOUN any vehicle that can fly
air force air forces
NOUN the part of a country’s armed services that fights using aircraft
airline airlines
NOUN a company that provides air travel
airmail
NOUN the system of sending letters and parcels by air • He sent letters from Hong Kong to Britain by airmail.
airport airports
NOUN a place where people go to catch aeroplanes
airtight
ADJECTIVE If something is airtight, no air can get in or out.
aisle aisles
NOUN a long, narrow gap that people can walk along between rows of seats or shelves • The ticket collector was coming down the aisle.
ajar
ADJECTIVE A door or window that is ajar is slightly open.
alarm alarms, alarming, alarmed
NOUN 1 a feeling of fear and worry • The cat sprang back in alarm.
2 an automatic device used to warn people of something • The burglar alarm went off accidentally.
VERB 3 If something alarms you, it makes you worried and anxious.
album albums
NOUN 1 a CD, cassette or record with a number of songs on it
2 a book in which you keep a collection of things, such as photographs or stamps
alcohol
NOUN the name for drinks such as beer, wine and spirits
alert alerts, alerting, alerted
ADJECTIVE 1 If you are alert, you are paying full attention to what is happening.
SYNONYMS: vigilant, watchful
VERB 2 If you alert someone to a problem or danger, you warn them of it.
algebra
NOUN a branch of mathematics in which symbols and letters are used to represent unknown numbers
alias aliases
NOUN a false name
alibi alibis
NOUN If you have an alibi, you have evidence proving you were somewhere else when a crime was committed.
alien aliens
NOUN 1 In science fiction, an alien is a creature from outer space.
ADJECTIVE 2 Something that is alien to you seems strange because it is not part of your normal experience. • The desert is an alien environment to many people.
[from Latin alienus meaning foreign]
alight alights, alighting, alighted
ADJECTIVE 1 Something that is alight is burning.
VERB 2 If something alights somewhere, it lands there.
3 If someone alights from a vehicle, they get out of it.
alike
ADJECTIVE 1 Things that are alike are very similar in some way.
ADVERB 2 If people or things are treated alike, they are treated the same.
alive
ADJECTIVE If someone or something is alive, they are living.
alkali alkalis
NOUN a chemical substance sometimes used in cleaning materials. Alkalis can neutralize acids.
ANTONYM: acid
alkaline ADJECTIVE
all
ADJECTIVE, NOUN OR ADVERB 1 the whole of something • She told us all about it. • He ate all the chocolate.
ADVERB 2 also used to show that both sides in a game or contest have the same score • The final score was three points all.
Allah
PROPER NOUN the Muslim name for God
allege alleges, alleging, alleged
VERB If you allege that something is true, you say it’s true, but you cannot prove it.
allergy allergies
NOUN If you have an allergy to something, it makes you ill to eat or touch it.
allergic ADJECTIVE
alley alleys
NOUN a narrow street or passageway between buildings
alliance alliances
NOUN a group of countries, organizations or people who have similar aims and who work together to achieve them
alligator alligators
NOUN a large, scaly reptile, similar to a crocodile
[from Spanish el lagarto meaning lizard]
alliteration
NOUN the use of several words together that begin with the same letter or sound. For example, the slithery snake slid silently across the sand.
allotment allotments
NOUN a piece of land that people rent to grow fruit and vegetables on
allow allows, allowing, allowed
VERB If someone allows you to do something, they let you do it.
all right
ADJECTIVE 1 If something is all right, it is satisfactory, but not especially good. • Do you like mushrooms? They’re all right.
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