Origin: 1725–35; < L rubēscent- (s. of rubēscēns, prp. of rubēscere to redden), equiv. to rub(ēre) to be red (deriv. of ruber red; see ruby) + -ēsc- inchoative suffix + -ent--ent
[Latin rubēscēns, rubēscent-, present participle of rubēscere, to grow red, inchoative of rubēre, to be red; see reudh- in Indo-European roots.] ru·bes'cence n.