What's the difference between unswell and upswell?

Unswell

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Definition:

• (v. t.) To sink from a swollen state; to subside.

Example Sentences:

• (1) Facial blushing, the only undefined and involuntary stimulus, is followed by an unswelling and a decrease of mucous membrane temperature.

Upswell

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Definition:

• (v. i.) To swell or rise up.

Example Sentences:

• (1) It's no surprise that there has been an upswell of public concern at the prospect that our island's natural life might be auctioned off at a government-sponsored jumble sale.