Englishfor English speakers
retract
Verb
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If something retracts, it pulls back into where it came out from.
An airplane retracts its wheels after takeoff.
As she stretched, the cat's claws extended and then retracted again.
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If you retract something you said, you take back or withdraw it.
I retract all the accusations I made about the senator and sincerely hope he won't sue me.
homotopy
noun
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(topology) A continuous deformation of one continuous function to another.
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(topology) A theory associating a system of groups with each topological space.
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(topology) system of groups associated with a topological space