extenuate

To make (something) less dense, or thinner; also, to lower the viscosity of (something).

Garlyke. It doth extenuate and cutte groſſe humours and ſlymy, diſſolueth groſſe wyndes, and healeth all the body; […] yf it be ſodden vntyll it loſeth his tarteneſſe, it ſomewhat nouryſſheth, and yet looſeth not his propertie, to extenuate groſſe humours: […]

[T]hey ſuppoſe an Olive the more grovvne it is in carnoſitie, to be the fuller of oile: vvhereas in very truth, all the good juice in them is converted then into the groſſe and corpulent ſubſtance thereof, […] unleſſe there enſue a drie ſeaſon and faire vveather to extenuate that groſſe ſubſtance into vvhich the Olive had turned the foreſaid juice and humour, all the oile is conſumed and loſt.

To make (someone or something) slender or thin; to emaciate, to waste.

It was deemed meritorious to disfigure the body by neglect and filth, to extenuate it by fasting and watchfulness, to lacerate it with stripes, and to fret the wounds with cilices of horsehair.

Mamma's reception of her, just off the long winter journey, and extenuated with fatigues and sickly chagrins, was of the most cutting cruelty: "What do you want here? What is a medicant like you come hither for?"

To underestimate or understate the importance of (something); to underrate.

The Company having novv pretty vvell ſatisfied their Thirſt, nothing remained but to pay the Reckoning, a Circumſtance often productive of much Miſchief and Diſcontent among the inferior Rank of Gentry; vvho are apt to find great Difficulty in aſſeſſing the Sum, vvith exact Regard to diſtributive Juſtice, vvhich directs, that every Man ſhall pay according to the Quantity vvhich he drinks. […] In this Controverſy, the vvhole Company ſpoke together, and every Man ſeemed vvholly bent to extenuate the Sum vvhich fell to his Share; […]

To underestimate or understate the importance of (something); to underrate.

to extenuate his faults    to extenuate their crimes

I knovv vvhat you vvould ſay: if I haue knovvne her, / You vvill ſay, ſhe did imbrace me as a husband, / And ſo extenuate the forehand ſinne: No, Leonato, / I never tempted her vvith vvord too large; / But as a brother to his ſiſter, ſhevved / Baſhful ſinceritie, and comelie loue.

To beat or draw (a metal object, etc.) out so as to lessen the thickness.

[T]he Chinians can very cunningly beate and extenuate gold into plates and leaues.

His [the sawfish's] Trunk or Body preſently behind his Head, becomes five inches broad, and about three high; from whence it is again extenuated all the way to the end of his Tail.

Of a person: emaciated, wasted, weakened; of the body or part of it: atrophied, shrunken, withered.

Of a quality or thing: lessened, weakened.

And, that ſame Maieſty, vvhich (as the Baſe / And Pedeſtal) ſupports the vvaight and grace, / Greatnes and glory of a vvell-Rul'd State, / It not extinguiſht nor extenuate, / By being parcelliz'd to a plurality / Of petty Kinglings, of a mean Equality: […]

VVee repreſent Small Sounds as Great and Deepe; Likevviſe Great Sounds, Extenuate and Sharpe; VVee make diuerſe Tremblings and VVarblings of Sounds, vvhich in their Originall are Entire.

Reduced to poverty; impoverished.