I came across this word in an English test, where "hardwork" was marked as the 'correct' answer for a question. I know of the adjective hardworking, but I thought "hardwork" was always written as two words, like "hard work".
An online search for "hardwork" reveals some results, but most of them seem to use the two-word version ("hard work"). This page on Definitions.net is the only dictionary I found mentioning "hardwork" as a single word. Is that a valid alternate spelling, and if so, where/when has it been used in the past?