tumescence
Tumescence (noun) means swelling caused by a build-up of fluid in part of the body.
Etymology
First recorded in 1725, the word comes from French tumescence, from Latin tumescēns (“swelling”), the present participle of tumēscō (“to begin to swell”), itself formed from tumeō (“to swell”) and -ēscō (an incohative suffix; English -esce, here -escence). The stem traces to Proto-Indo-European *tum-éh₁- (“to be swelling”), the stative stem of *tum- (“to swell”).