5 MODAL If you say that one thing must have happened in order for something else to happen, you mean that it is necessary for the first thing to have happened before the second thing can happen. □ In order to take that job, you must have left another job.
6 MODAL You use must to express your intention to do something. □ I must be getting back. □ I must phone my parents. □ He told the Prime Minister that he felt he must now leave.
7 MODAL You use must to make suggestions or invitations very forcefully. □ You must see a doctor, Frederick. □ You must see the painting Paul has given me as a wedding present.
8 MODAL You use must in remarks and comments where you are expressing sympathy. □ This must be a very difficult job for you.
9 MODAL You use must in conversation in expressions such as ' I must say ' and ' I must admit ' in order to emphasize a point that you are making. [EMPHASIS ] □ This came as a surprise, I must say. □ I must admit I like looking feminine.
10 MODAL You use must in expressions such as ' it must be noted ' and ' it must be remembered ' in order to draw the reader's or listener's attention to what you are about to say. □ It must be noted, however, that not all British and American officers carried out orders. □ It must be stated that this illness is one of the most complex conditions known to man.
11 MODAL You use must in questions to express your anger or irritation about something that someone has done, usually because you do not understand their behaviour. [FEELINGS ] □ Why must she interrupt? □ Must you always run when the pressure gets too much?
12 MODAL You use must in exclamations to express surprise or shock. [EMPHASIS ] □ 'Go! Please go.'—'You must be joking!' □ I really must be quite mad!
13 N‑COUNT If you refer to something as a must , you mean that it is absolutely necessary. [INFORMAL ] □ The new 37th issue of National Savings Certificates is a must for any taxpayer.
14 PHRASE You say ' if you must ' when you know that you cannot stop someone doing something that you think is wrong or stupid. □ If you must be in the sunlight, use the strongest filter cream you can get. □ 'Could I have a word?'—'Oh dear, if you must.'
15 PHRASE You say ' if you must know ' when you tell someone something that you did not want them to know and you want to suggest that you think they were wrong to ask you about it. □ 'Why don't you wear your jogging shorts Mum?'—'Well, my legs are too skinny, if you must know.'
must- /mʌ st-/ COMB Must- is added to verbs such as 'see', 'have', or 'read' to form adjectives and nouns which describe things that you think people should see, have, or read. For example, a must-have is something which you think people should get, and a must-win game is one which a team needs to win. [JOURNALISM , INFORMAL ] □ …a list of must-see movies.
mus|tache /məstɑː ʃ, [AM ] mʊ stæʃ/ → see moustache
mus|tang /mʌ stæŋ/ (mustangs ) N‑COUNT A mustang is a small wild horse which lives on the plains of North America.
mus|tard /mʌ stə r d/ (mustards )
1 N‑VAR Mustard is a yellow or brown paste usually eaten with meat. It tastes hot and spicy. □ …a pot of mustard.
2 COLOUR Mustard is used to describe things that are brownish-yellow in colour. □ …a mustard-coloured jumper.
3 PHRASE [usu with neg] If someone does not cut the mustard , their work or their performance is not as good as it should be or as good as it is expected to be. [INFORMAL ]
mu s|tard and cre ss N‑UNCOUNT Mustard and cress is very young mustard plants and cress plants grown together and eaten in salad.
mu s|tard gas N‑UNCOUNT Mustard gas is a gas which burns the skin and was used in war as a weapon.
mu s|tard pow|der N‑UNCOUNT Mustard powder is a yellow powder. You add hot water to it in order to make mustard.
mus|ter /mʌ stə r / (musters , mustering , mustered )
1 VERB If you muster something such as support, strength, or energy, you gather as much of it as you can in order to do something. □ [V n] He travelled around West Africa trying to muster support for his movement.
2 VERB When soldiers muster or are mustered , they gather together in one place in order to take part in a military action. □ [V ] The men mustered before their clan chiefs. □ [V n] The general had mustered his troops north of the Hindu Kush.
3 PHRASE If someone or something passes muster , they are good enough for the thing they are needed for. □ I could not pass muster in his language. □ If it doesn't pass muster, a radio station could have its license challenged.
mu st-ha ve (must-haves ) N‑COUNT A must-have is something modern that many people want to have. □ The mobile phone is now a must-have for children. ● ADJ Must-have is also an adjective. □ …a must-have fashion accessory.
mustn't /mʌ s ə nt/ Mustn't is the usual spoken form of 'must not'.
must've /mʌ stəv/ Must've is the usual spoken form of 'must have', especially when 'have' is an auxiliary verb.
mus|ty /mʌ sti/ (mustier , mustiest ) ADJ Something that is musty smells old and damp. □ …that terrible musty smell.
mu|tant /mjuː t ə nt/ (mutants ) N‑COUNT A mutant is an animal or plant that is physically different from others of the same species because of a change in its genes.
mu|tate /mjuːte I t, [AM ] mjuː te I t/ (mutates , mutating , mutated )
1 VERB If an animal or plant mutates , or something mutates it, it develops different characteristics as the result of a change in its genes. □ [V ] The virus mutates in the carrier's body. □ [V + into ] A newer anti-HIV drug caused HIV to mutate into a form which could not infect new cells. □ [V n] The technique has been to mutate the genes by irradiation or chemicals. [Also V n + into ] ● mu|ta|tion /mjuːte I ʃ ə n/ (mutations ) N‑VAR □ Scientists have found a genetic mutation that appears to be the cause of Huntington's disease.