noun
nausea; urge to vomit
Medical term for the sensation of nausea or feeling sick to one's stomach. In casual contexts, 吐き気 is more common.
抗がん剤の副作用で悪心が続いている。
I have persistent nausea as a side effect of the anticancer drug.
食後すぐに悪心を感じた。
I felt nausea right after eating.
吐き気 is the common, everyday word for nausea. 悪心 is a more formal medical term.
Sino-Japanese compound of 悪 (bad, unpleasant) and 心 (heart, mind), originally referring to a disturbed state of mind or body. The modern medical sense 'nausea' is a specialized usage.