Simple Definition of deleterious

from our Learner's Dictionary

deleterious

adjective

formal : damaging or harmful
The chemical is deleterious to the environment.
The drug has no deleterious effects on patients.

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“Deleterious.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/deleterious. Accessed 24 Jun. 2026.

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