U

Primary Meanings of U

1.
n
the 21st letter of the Roman alphabet
2.
n
a heavy toxic silvery-white radioactive metallic element; occurs in many isotopes; used for nuclear fuels and nuclear weapons
3.
n
a base containing nitrogen that is found in RNA (but not in DNA) and derived from pyrimidine; pairs with adenine
Full Definitions of U
1

n the 21st letter of the Roman alphabet

Synonyms:
u
Type of:
alphabetic character, letter, letter of the alphabet
the conventional characters of the alphabet used to represent speech
2

n a heavy toxic silvery-white radioactive metallic element; occurs in many isotopes; used for nuclear fuels and nuclear weapons

Synonyms:
atomic number 92, uranium
Types:
uranium 235
a uranium isotope with mass number 235; capable of sustaining chain reactions
uranium 238
the commonest isotope of uranium; it is not fissionable but when irradiated with neutrons it produces fissionable plutonium 239
Type of:
metal, metallic element
any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.
3

n a base containing nitrogen that is found in RNA (but not in DNA) and derived from pyrimidine; pairs with adenine

Synonyms:
uracil
Type of:
base, nucleotide
a phosphoric ester of a nucleoside; the basic structural unit of nucleic acids (DNA or RNA)

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