deleterious
harmful
Roots
- -ous / -ious: full of or marked by a quality
- deleter: harm, damage, or destroy
Deleterious is damage in a calm voice: something quietly harms the system it touches.
The report warned that chronic sleep loss has deleterious effects on memory, mood, and judgment.
Deleterious is damage in a quiet suit. The word sounds formal, but the picture is simple: something enters a system and makes it worse.
A deleterious habit, drug, policy, or rumor may not look dramatic at first. The word is useful because it names harm that can sound clinical, gradual, or hidden while still doing real damage.