(Archaic, rare) Becoming or growing fat; also of a food: greasy, fattening.
The process of becoming fat: fatness, obesity; (in extended use) oiliness, unctuousness.
I saw Dr Gregory (Biographer of Chatterton) to-day; a very brown-looking man, of most pinguescent and full-moon cheeks. There is much tallow in him. (Joseph Cottle, Reminiscences of Samuel Taylor Coleridge and Robert Southey, 1848)
"I said she was pinguescent," Marny returned. "She is. 'Pinguescent' means 'getting fat'." Kendra burst out laughing. (Gwen Bristow, Calico Palace: A Novel)
Haggis, as the Doctor might say, is unctuously pinguescent and unfragantly odorous. (Fraser's Magazine for Town and Country, Vol 6, 1832)
He tells Voltore, for instance, that he may dream of swimming in 'golden lard'… The image identifies the lawyer's motive, infusing it at the same time with the resonance of repellent and excessive pinguescence. Everywhere in (Martin R Orkin, 'Languages of Deception in Volpone', Theoria: A Journal of Studies in the Arts, Humanities and Social Sciences, 1982)
Late 18th century; earliest use found in Robert Southey (1774–1843), poet and reviewer. From classical Latin pinguēscent-, pinguēscēns, present participle of pinguēscere to grow fat, to become oily or fatty from pinguis fat + -ēscere (Lexico)