Benign
Etymology
From Latin benignus, "kind, good-natured," a blend of bene, "well," and roots tied to gignere, "to be born" — literally "well-born" or good by nature. In medicine it describes a tumor that grows slowly and stays local rather than invading. Outside medicine it keeps its gentler sense: a benign remark or a benign climate.
adjective · /bih-NINE/
Harmless in nature — especially a growth that stays put and does not spread or invade.
What it names
The single most reassuring word after a biopsy, and a useful everyday term for anything that looks worrying but turns out safe.
Example
The lump turned out to be benign, and the whole family exhaled.
Related idea
Malignant is its dangerous opposite — a growth that invades and spreads.
adjective · /bih-NINE/
Gentle, kindly, or harmless in nature; doing no damage.
What it names
a mild manner, a favorable climate, a well-meant act
Example
A benign smile; benign neglect.
Related idea
The opposite of malignant in this general sense too; from Latin “benignus” (kind).