Etymology
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deleterious (adj.)

1640s, "noxious, poisonous," from Medieval Latin deleterius, from Greek dēlētērios "noxious," from dēlētēr "destroyer," from dēlēisthai "to hurt, injure," of which Beekes writes, "the verb is probably non-IE, i.e. Pre-Greek." From 1823 as "mentally or morally hurtful or injurious." Related: Deleteriously; deleteriousness.

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Definitions of deleterious

deleterious (adj.)
harmful to living things;
deleterious chemical additives
Synonyms: hurtful / injurious
From wordnet.princeton.edu