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"harmful" is also used as a crossword clue. If that's what you saw, the answer is often detrimental (11 letters).
Definitions
causing or capable of causing harm
Word origin
From Middle English harmful, from Old English *hearmful (suggested by hearmfullīċ (“harmful; hurtful”)), equivalent to harm + -ful.
Used in a sentence
“Wear a hat to protect your skin from harmful sunlight.”
“Smoking is harmful to the lungs.”
“Burning fossil fuels is harmful to the environment.”
Source: Wiktionary, CC BY-SA 4.0
Used as a crossword answer1 curated clues
01“Damaging”7 letters
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