Definition of "impracticable"

And yet this tough impracticable heart / Is govern'd by a dainty-finger'd girl ; […]

1713, Nicholas Rowe, The Fair Penitent‎, published 1797

H. is a person of extraordinary health & vigor, of unerring perception, & equal expression; and yet he is impracticable, and does not flow through his pen or (in any of our legitimate aqueducts) through his tongue.

c. 1841, Ralph Waldo Emerson, Journals and Miscellaneous Notebooks‎, published 1960, page 18

They were not allowed, of course, to join us in the sitting room, partly that their practice might not be disturbed, but principally, that I was looked upon as an utter impracticable.

1829, Henry Barkley Henderson, The Bengalee, or Sketches of Society and Manners in the East‎, page 13

The strict constructionists had dwindled to a few impracticables, headed by John Randolph.

1867, James Parton, Famous Americans of Recent Times‎, page 83

Then there are the gladiators, to whom it is always a battle; 't is no matter on which side, they fight for victory; then the heady men, the egotists, the monotones, the steriles, and the impracticables.

1870, Ralph Waldo Emerson, “Clubs”, in Society and Solitude. Twelve Chapters, Boston, Mass.: Fields, Osgood, & Co., page 208