Englishfor English speakers
nucleus
Noun
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A nucleus is the center of a cell or atom.
—
The center of anything.
of
Preposition
—
Made using.
It is a house of cards.
comet
Noun
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An object in outer space in an orbit that has dust surrounding its main mass, including a tail formed from gas from the comet.
I could see the bright blue comet passing my window at night.