Collins COBUILD Advanced Learner’s Dictionary

ubiqui|tous /juːb I kw I təs/ ADJ If you describe something or someone as ubiquitous , you mean that they seem to be everywhere. [FORMAL ] □  Sugar is ubiquitous in the diet. □  She is one of the wealthiest, most ubiquitous media personalities around.

ubiquity /juːb I kw I ti/ N‑UNCOUNT If you talk about the ubiquity of something, you mean that it seems to be everywhere. [FORMAL ]

ud|der /ʌ də ^r / (udders ) N‑COUNT A cow's udder is the organ that hangs below its body and produces milk.

UFO /juː ef oʊ , juː foʊ/ (UFOs ) N‑COUNT A UFO is an object seen in the sky or landing on Earth which cannot be identified and which is often believed to be from another planet. UFO is an abbreviation for 'unidentified flying object'. □  There has been a surge of UFO sightings in America.

Ugan|dan /juːgæ ndən/ (Ugandans )

1 ADJ Ugandan means belonging or relating to Uganda or to its people or culture.

2 N‑COUNT A Ugandan is a Ugandan citizen, or a person of Ugandan origin.

ugh EXCLAM Ugh is used in writing to represent the sound that people make if they think something is unpleasant, horrible, or disgusting. □  Ugh–it was horrible.

ugly /ʌ gli/ (uglier , ugliest )

1 ADJ If you say that someone or something is ugly , you mean that they are very unattractive and unpleasant to look at. □  …an ugly little hat. □  She makes me feel dowdy and ugly. ●  ug|li|ness N‑UNCOUNT □ [+ of ] …the raw ugliness of his native city.

2 ADJ If you refer to an event or situation as ugly , you mean that it is very unpleasant, usually because it involves violent or aggressive behaviour. □  There have been some ugly scenes. □  The confrontation turned ugly. ●  ug|li|ness N‑UNCOUNT □ [+ of ] …the subtlety and ugliness of sexual harassment.

3to rear its ugly head → see rear

u gly du ck|ling (ugly ducklings ) N‑COUNT [usu sing] If you say that someone, especially a child, is an ugly duckling , you mean that they are unattractive or awkward now, but will probably develop into an attractive and successful person.

UHF /juː e I tʃ e f/ N‑UNCOUNT [oft N n] UHF is a range of radio waves which allows a radio or television receiver to produce a good quality of sound. UHF is an abbreviation for 'ultra-high frequency'. □  …Boston UHF channels.

uh huh also uh-huh CONVENTION Uh huh is used in writing to represent a sound that people make when they are agreeing with you, when they want to show that they understand what you are saying, or when they are answering 'yes' to a question. [INFORMAL ] □  'Did she?'—'Uh huh.'

UHT /juː e I tʃ tiː / ADJ [usu ADJ n] UHT is used to describe milk which has been treated at a very high temperature so that it can be kept for a long time if the container is not opened. UHT is an abbreviation for 'ultra-heat-treated'. [BRIT ]

UK ◆◇◇ /juː ke I / N‑PROPER The UK is Great Britain and Northern Ireland. UK is an abbreviation for 'United Kingdom'.

uku|lele /juː kəle I li/ (ukuleles ) also ukelele N‑COUNT A ukulele is a small guitar with four strings.

ul|cer /ʌ lsə ^r / (ulcers ) N‑COUNT An ulcer is a sore area on the outside or inside of your body which is very painful and may bleed or produce an unpleasant poisonous substance. □  …stomach ulcers.

ul|cer|at|ed /ʌ lsəre I t I d/ ADJ If a part of someone's body is ulcerated , ulcers have developed on it. □  …ulcerated mouths. □  Every inch of his arms and legs was ulcerated.

ul|te|ri|or /ʌlt I ə riə ^r / ADJ [ADJ n] If you say that someone has an ulterior motive for doing something, you believe that they have a hidden reason for doing it. □ [+ for ] Sheila had an ulterior motive for trying to help Stan.

ul|ti|mate ◆◇◇ /ʌ lt I mət/

1 ADJ [ADJ n] You use ultimate to describe the final result or aim of a long series of events. □  He said it is still not possible to predict the ultimate outcome. □  The ultimate aim is to expand the network further.