Englishfor English speakers
extensive
Adjective
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Extensive research, experience, damage, etc. is large in size, amount, or degree.
There has been extensive research into ways to improve schools.
She has extensive experience working with these computer systems.
After the wild fires, the damage was extensive.
defect
Noun
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A defect in something is a mistake or problem that makes the thing not perfect.
This gem has a defect, so it is not worth much.
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A defect is something that is not perfect.
defect
Verb
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If you defect from a group or country, you leave it and join a different side.
In 1961, defected from Russia.