U
/ju:/
Học thuậtThân thiện
Definition
Noun:
- The 21st letter of the modern English alphabet: A letter, written in uppercase as "U" and lowercase as "u".
- A representation of the sound /juː/ or /ʌ/: The speech sound associated with this letter, as in "use" (/juːz/) or "cup" (/kʌp/).
- (Chemistry) Symbol for uranium: The chemical symbol for the radioactive metallic element uranium (atomic number 92).
- (Biochemistry) Abbreviation for uracil: In molecular biology, a nitrogenous base found in RNA.
Adjective (chiefly British):
- Upper-class; characteristic of the upper social class: Used to describe language, behavior, or style considered typical of the upper class, especially in contrast to "non-U" (non-upper-class).
Examples of Usage
Noun:
- The word "umbrella" starts with the letter u.
- Uranium, represented by the symbol U, is used in nuclear reactors.
- In RNA, u (uracil) pairs with adenine.
Adjective:
- Her pronunciation was considered very U.
- Using the term "serviette" instead of "napkin" was once deemed non-U.
Advanced Usage
- "U-turn": A complete reversal of policy, opinion, or direction. (Note: This is a compound word listed separately as a variant).
- In academic grading: In some educational systems, "U" can stand for "Ungraded" or "Unclassified".
Variants and Related Words
- Uppercase U, Lowercase u: The two forms of the letter.
- U-bend: A pipe fitting shaped like the letter U.
- U-turn (n): A turn made by a vehicle to reverse its direction, resembling the shape of the letter U; figuratively, a complete change in plan or opinion.
- U-shaped (adj): Having a shape similar to the letter U.
Synonyms
- Uranium (when used as the chemical symbol).
- Uracil (when used as the biochemical abbreviation).
- Upper-class (for the adjectival sense).
Related Phrases and Idioms
- Mind your p's and q's (and u's): An extension of the idiom meaning to be careful about one's behavior or details, humorously including the letter 'u'. (Note: This is a playful, non-standard variant of the common idiom).
Adjective
- (chiefly British) of or appropriate to the upper classes especially in language use
Noun
- the 21st letter of the Roman alphabet
- a heavy toxic silvery-white radioactive metallic element; occurs in many isotopes; used for nuclear fuels and nuclear weapons
- a base containing nitrogen that is found in RNA (but not in DNA) and derived from pyrimidine; pairs with adenine