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"burdensome" is also used as a crossword clue. If that's what you saw, the answer is often onerous (7 letters).
Definitions
not easily borne; wearing
Word origin
From burden + -some.
Used in a sentence
“. . . reap a pleasure from what, to the generality of mankind, may seem burdensome and laborious.”
“Finally, there are the commuter trains. Both companies operate these around the big cities and both find them burdensome, owing to the lack of off-peak travel.”
Source: Wiktionary, CC BY-SA 4.0
Used as a crossword answer1 curated clues
01“Hard to carry”10 letters
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