The Vocalibrate dictionary

deleterious

US/ˌdɛləˈtɪriəs/GB/ˌdɛlɪˈtɪəriəs/adjective

harmful or damaging

Lack of sleep has a deleterious effect on memory.

Near in meaning: harmfuldamagingdetrimentalinjurious
In the family: deleteriouslydeleteriousness

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