untruly

A mischief-maker, quite untruly, informs the heroine's aunts, who are her guardians—Catholics of the strictest type—that the hero is still carrying on an old intrigue with a beautiful Frenchwoman, now living at Nice.

From Memoirs of Life and Literature by W. H. (William Hurrell) Mallock

If you have so spoken, you have said untruly, and have lied in your throat, which I will maintain, God willing, against you, as becomes me of honour and duty.

From Life of Mary Queen of Scots, Volume II (of 2) by Henry Glassford Bell

The seventy miles from Launceston to Mount’s Bay have been called not untruly “the dreariest strip of earth traversed by any English high road.”

From Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 4 "Coquelin" to "Costume" by Various

Such treaties did they cite, and not untruly; for by one shameful compact, you bartered the glories of Blenheim for the traffic in blood.

From Thoughts on African Colonization by William Lloyd Garrison

And after this pattern we least untruly and least unworthily conceive the mode of that eternal and universal Progress which is the life of the Whole within and as part of which we live.

From Progress and History by Francis Sydney Marvin