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Alternative forms[edit]


Borrowed (1640s, 1582 as deletorious) from Medieval Latin deleterius, deletorius, from Ancient Greek δηλητήριος (dēlētḗrios, noxious, deleterious), from δηλητήρ (dēlētḗr, a destroyer), from δηλέομαι (dēléomai, I hurt, damage, spoil, waste).[1]



deleterious (comparative more deleterious, superlative most deleterious)

  1. Harmful often in a subtle or unexpected way.
    Synonyms: destructive, harmful, hurtful, injurious, noxious, pernicious; see also Thesaurus:harmful
    deleterious effects
    deleterious to someone's health
    • 1850, Nathaniel Hawthorne, “chapter XV”, in The Scarlet Letter:
      Or might it suffice him, that every wholesome growth should be converted into something deleterious and malignant at his touch?
    • 2017 September, Jean M. Twenge, “Have Smartphones Destroyed a Generation?”, in The Atlantic[1]:
      The advent of the smartphone and its cousin the tablet was followed quickly by hand-wringing about the deleterious effects of “screen time.” But the impact of these devices has not been fully appreciated, and goes far beyond the usual concerns about curtailed attention spans.
  2. (genetics) Having lower fitness.

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Further reading[edit]


  1. ^ Douglas Harper (2001–2022), “deleterious”, in Online Etymology Dictionary.