醫學上的惡性
醫學把「會往外傷人的壞」搬進身體裡：一個不肯待在原地、會侵入別處的腫瘤，正好是這個畫面。相對的 benign 就是待著不動、不傷人的那一種。
noun · C1
A growth in the body that is cancer - one that can spread into other parts and do serious harm, as opposed to a harmless lump.
惡性腫瘤
核心畫面
One way to hold this word: something bad that will not stay where it is. It is not merely unpleasant in itself - it reaches out and damages whatever is near it. Medicine uses that picture for a growth that invades the rest of the body; writers use it for hatred that spreads through a person and out towards other people.
「malignancy」的核心畫面可以想成一種壞東西，而且是不肯待在原地的那種壞。它不只是自己不好看、不舒服。它會往…更多收起
「malignancy」的核心畫面可以想成一種壞東西，而且是不肯待在原地的那種壞。它不只是自己不好看、不舒服。它會往外伸，傷到旁邊的東西。醫學把這個畫面用在腫瘤上：一個會侵入其他部位的腫瘤。寫人的時候用在恨上：一種在心裡蔓延、然後往別人身上去的惡意。兩邊共用的不是「病」，是「會擴散的壞」。From the word’s history
Wiktionary derives the word from malignant plus -cy, or malign plus -ancy, or Latin malignantia. The adjective malign is the older piece, and it names ill will; the noun simply names the state of being that way, which is why the medical and the human uses sit on one word.
依據來源，這個字可以看成 malignant 加 -cy，或 malign 加 -ancy，也可能直接來自拉丁文 malignantia。比較早的那一塊是 malign，講的是「帶著惡意」。名詞只是把那個狀態說出來。所以醫學的用法和寫人的用法才會共用同一個字。
Wiktionary, entry malignancy (packet source_ref kaikki:3f6f69a190036ae4:1056080045:9049)
From the picture
Also in this word
noun · C2
A deep, settled feeling of hatred towards someone, strong enough that the person wants to see them suffer.
惡意／怨毒