Englishback-breaking
adjective
a back-breaking task:
gruelling, arduous, strenuous, onerous, punishing, murderous, crushing, Herculean, demanding, exacting, taxing, formidable, exhausting, draining, laborious, burdensome, tough, stiff, uphill, heavy;
informal killing;
British, informal knackering;
archaic toilsome.
▷antonyms easy, effortless.
back-breaking Oxford Dictionary of English