Hardscrabble is an English word (originally an Americanism) that began as a noun but is now chiefly used as an adjective to denote a state of bare subsistence in which great effort is expended for paltry reward.
In fact, even as an adjective the word's usage has become highly circumscribed, such that it is almost always paired with the words "life" or "existence," as in the canonical usage example of "the sharecropper's hardscrabble life," which is cited by more than a few dictionaries.
Etymologically, the word derives from the English word to "scrabble," meaning to scratch, rake, dig, or plow. In the early days of the American republic, the "hard scrabble" referred to those sections of the American prairie that were dry, hard, and rocky and thus required great effort to "scrabble" or plow. From this usage eventually developed the idea of a "hardscrabble life" in which day to day living was as difficult as trying to plow up dry, rock-hard prairie.