From Wiktionary, the free dictionary
Adapted borrowing (1640s; 1582 as deletorious) of New Latin dēlētērius, dēlētōrius + -ous, from Ancient Greek δηλητήριος (dēlētḗrios, “noxious, deleterious”), from δηλητήρ (dēlētḗr, “a destroyer”), from δηλέομαι (dēléomai, “I hurt, damage, spoil, waste”).[1][2][3] Not related to delete or deleble. Doublet of deletery.
deleterious (comparative more deleterious, superlative most deleterious)
deleterious effects
deleterious to someone's health
1946 May and June, J. G. Holmes, “The North Woolwich Branch”, in Railway Magazine, page 176:
A trolleybus service was established by the London Passenger Transport Board between North Woolwich and Stratford on February 6, 1938, and had a deleterious effect on railway passenger traffic.
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.
A deleterious mutation
harmful
