畢業

The Japanese entertainment/fandom slang meaning of "to graduate (to leave a group)" is a Semantic loan from Japanese 卒(そつ)業(ぎょう) (sotsugyō).

畢⫽業 (verb-object) (intransitive)

1. to graduate; to finish school

   畢業典禮／毕业典礼  ―  bìyè diǎnlǐ  ―  graduation ceremony; commencement

   畢業以來／毕业以来  ―  bìyè yǐlái  ―  since graduation

   延期畢業／延期毕业  ―  yánqī bìyè  ―  to defer graduation

   我去年中學畢業了。 [MSC, trad.]
   我去年中学毕业了。 [MSC, simp.]

   Wǒ qùnián zhōngxué bìyè le.

   I graduated from high school last year.

   畢業後，他仍然與同學保持聯繫。 [MSC, trad.]
   毕业后，他仍然与同学保持联系。 [MSC, simp.]

   Bìyè hòu, tā réngrán yǔ tóngxué bǎochí liánxì.

   He still keeps in touch with his classmates after graduation.

2. (Japanese entertainment fandom slang) to graduate (to leave a group)
3. (figurative, business) to quit ; to be fired

   歡歡：在京東工作五年，一周內「畢業」 [MSC, trad.]
   欢欢：在京东工作五年，一周内「毕业」 [MSC, simp.]

   Huānhuān: zài Jīngdōng gōngzuò wǔ nián, yī zhōu nèi “bìyè”

   Huanhuan: Worked for JD.com for five years and "stepped down" within a week.

Unlike its English equivalent graduate, 畢業／毕业 (bìyè) implies not only an event but a state. Note the following example sentence:

我畢業兩年了。／我毕业两年了。  ―  Wǒ bìyè liǎng nián le.  ―  I graduated two years ago.

Literally: "I have graduated for two years."