曇花一現

昙花一现
tánhuāyīxiàn
  1. lit. the night-blooming cactus shows once
  2. flash in the pan (idiom)
  3. short-lived

CEDICT

like a flash in the pan; ephemeral; short-lived; not long-term

Wiktionary

曇花，優曇婆羅華的簡稱，即無花果。印度傳說無花果只在聖王出世時才會開花。見隋．智顗《妙法蓮華經文句．卷四．上》。謂佛的出世、說法如優曇婆羅華出現，其含意有二：一說指在適當時機才會出現；一說指希有難得。後多用於比喻人或事物一出現便迅速消失。

重編國語辭典

事物稀有難得

維基詞典

Entry Composition

1 曇花 tánhuā Dutchman's pipe cactus, aka Queen of the Night cactus (Epiphyllum oxypetalum)
2 一 yī
  1. one
  2. single
  3. a (article)
  4. as soon as
  5. entire; whole; all; throughout
  6. "one" radical in Chinese characters (Kangxi radical 1)
  7. also pr. yāo for greater clarity when spelling out numbers digit by digit
3 現 xiàn
  1. to appear
  2. present
  3. now
  4. existing
  5. current

Related entries

三分鐘熱度 sānfēnzhōngrèdù
  1. brief period of enthusiasm
  2. flash in the pan
我的朋友總是三分鐘熱度，一年就換了三份工作。

My friend has had three jobs in a year; he never sticks to anything for long.

Source: Tatoeba

短命 duǎnmìng
  1. to die young
  2. short-lived