Tumescence
Tumescence , noun
[Latin tumescens, -entis, p.pr. of tumescere to swell up, v. incho. from tumere to swell.]
The act of becoming tumid; the state of being swollen; intumescence; -- applied especially to the state of swelling of the vascular tissue in the male and female sex organs when they have been stimulated to readiness for sexual intercourse.