Definition of "ruthful"

An if it please thee! why, assure thee, Lucius, / 'Twill vex thy soul to hear what I shall speak; / For I must talk of murders, rapes, and massacres, / Acts of black night, abominable deeds, / Complots of mischief, treason, villainies, / Ruthful to hear, yet piteously perform'd:

c. 1588–1593 (date written), William Shakespeare, “The Lamentable Tragedy of Titus Andronicus”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act V, scene i]

When last this ruthful month was come, / And in Linlithgow’s holy dome / The King, as wont, was praying; [...]

1808 February 22, Walter Scott, “Canto Fourth. The Camp.”, in Marmion; a Tale of Flodden Field, Edinburgh: […] J[ames] Ballantyne and Co. for Archibald Constable and Company, […]; London: William Miller, and John Murray, stanza XVI, page 202

Then he bestowed robes of honour on the nurses wet and dry and said to them, "Be ye ruthful over them and rear them after the goodliest fashion."

1898, Richard Francis Burton, transl., The Book of the Thousand Nights and a Night, volume 7