VERB If you accuse someone of doing something wrong, you say they have done it.
accusation NOUN
ace aces
NOUN 1 In a pack of cards, the ace is a card with a single symbol on it.
2 In tennis, an ace is a serve that the other player is unable to return.
ADJECTIVE 3 INFORMAL good or skilful • an ace squash player
ache aches, aching, ached
NOUN 1 a continuous, dull pain
VERB 2 If a part of your body aches, you feel a continuous, dull pain there.
achieve achieves, achieving, achieved
VERB If you achieve something, you are successful at doing it or at making it happen.
acid acids
NOUN 1 a chemical substance. Strong acids can damage skin, cloth and metal, for example sulphuric acid. Other acids, such as those found in citrus fruit and vinegar, are harmless.
ANTONYM: alkali
ADJECTIVE 2 If something has an acid taste, it tastes sharp or bitter.
ANTONYM: alkaline
[from Latin acidus meaning sour]
acid rain
NOUN rain that has been polluted by the burning of fossil fuels, such as coal and oil
acknowledge acknowledges, acknowledging, acknowledged
VERB 1 If you acknowledge a fact or a situation, you admit that it is true.
2 If you acknowledge someone, you show that you have seen and recognized them, by waving or saying hello.
3 If you acknowledge a message or a letter, you tell the person who sent it that you have received it.
acne
NOUN a skin disease that causes spots on the face and neck. Acne is common among teenagers.
acorn acorns
NOUN a nut that grows on oak trees
acquaintance acquaintances
NOUN someone you know slightly but not well
acre acres
NOUN a unit for measuring land. One acre is equal to 4840 square yards or about 4047 square metres.
acrobat acrobats
NOUN an entertainer who performs difficult gymnastic acts
[from Greek akrobates meaning someone who walks on tiptoe]
acrobatic ADJECTIVE
acrobatics PLURAL NOUN
acronym acronyms
NOUN a word made up of the initial letters of a phrase • NATO is an acronym, and stands for North Atlantic Treaty Organization.
across
PREPOSITION OR ADVERB 1 If you go across a place, you go from one side of it to the other. • We walked across Hyde Park.
2 Something that is situated across a road or river is on the other side of it.
act acts, acting, acted
VERB 1 If you act, you do something. • We have to act quickly in an emergency.
2 If you act in a particular way, you behave in that way. • You’re acting like a baby.
3 If you act in a play or film, you play a role in it.
NOUN 4 a single thing someone does • The rescue was a brave act.
5 An Act of Parliament is a law passed by the government.
6 Stage plays are divided into parts called acts.
action actions
NOUN 1 something you do for a particular purpose
2 a physical movement, such as jumping
active
ADJECTIVE 1 Someone who is active moves around a lot or does a lot of things.
2 In grammar the active, or the active voice, is the form of the verb in which the subject of the sentence is the person or thing doing the action, rather than having it done to them. For example, the sentence The dog bit Ben is in the active voice. In the passive voice the subject is acted upon: Ben was bitten by the dog.
ANTONYM: passive
activity activities
NOUN 1 a situation in which a lot of things are happening at the same time • There was a great deal of activity in the hall as we got ready for the school play.
2 something you do for pleasure, such as gymnastics or music
actor actors
NOUN a man or woman whose job is performing in plays or films
actress actresses
NOUN a woman whose profession is acting
actual
ADJECTIVE real, rather than imaginary or guessed at • You guessed I was eleven – my actual age is twelve.
actually ADVERB
acute
ADJECTIVE 1 severe or intense • She had an acute pain in her arm.
2 In mathematics, an acute angle measures less than 90 degrees.
3 Someone who is acute is intelligent.
AD
ADJECTIVE You use AD in dates to show the number of years after the birth of Jesus Christ.
[an abbreviation of the Latin Anno Domini meaning the year of Our Lord]
adapt adapts, adapting, adapted
VERB 1 If you adapt to something, you get used to it.
2 If you adapt something, you change it so that it can be used in a new way.
adaptable
ADJECTIVE If you are adaptable, you change easily in a new situation or to suit new circumstances.
add adds, adding, added
VERB 1 If you add something to a number of things, you put it with those things. • Each girl added more wood to the pile.
2 If you add numbers together, or add them up, you work out the total. • Two and three added together are five (2 + 3 = 5).
adder adders
NOUN a small, poisonous snake
addiction addictions
NOUN If you have an addiction to something, you cannot stop doing it or wanting it.
addition additions
NOUN 1 the process of adding two or more numbers together
2 something that is added to something else • The addition of sugar would improve the taste of these plums.
additional
ADJECTIVE extra or more
additive additives
NOUN something that is added to something else, such as food
address addresses, addressing, addressed
NOUN 1 Your address is the number of the house where you live, together with the name of the street and the town or village.
VERB 2 If someone addresses a letter to you, they write