Withdrawal in order to make oneself inconspicuous(noun)
A shortening, or thinning, of the cervix before or during early labour(noun)
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Use "effacement" in a sentence
"And October steals in on silvery skies, but no rain; the light breaks through; roses are still growing; a slow effacement is at work in the sound of the still-green trees at the cusp of autumn."
"The thinning and shortening is called effacement, and is measured in percent, from 0 to 100."
"And in the Ethical Culture movement the effacement is complete."