1.
alternating between joy and worry; emotional ups and downs
The state of being emotionally affected by every small development, swinging between happiness and anxiety.
一喜一憂 names the state of being lifted and cast down by every small turn of events. Literally "one joy, one worry".
Usage
- Almost always used as a verb with する, and what one is reacting to takes に: 結果に一喜一憂する
- The negative forms are the commonest of all, because the word usually appears in advice not to overreact: 一喜一憂せずに, 一喜一憂しない
- Typical contexts are share prices, exam results, medical test numbers, and sports scores — anything that produces a stream of small readings
The word carries mild disapproval of the swinging itself. Calling someone 一喜一憂している suggests they are letting short-term noise govern their mood, and the recommended alternative is usually 冷静に (calmly).