plunge/ pl^nʤ /

1.noun [c] [of person] 
(fall) 跳入

2.noun [in prices] [ rates] 
猛跌

3.vt.[+knife] [ hand etc] 
to plunge sth into sth 把某物猛插入另一物

4.vt.
to be plunged into darkness/chaos 陷入黑暗/混乱

5.vi.
to plunge into sth (fall) 撞入某处

6.vi.
(leap) 跳入某处

7.vi.[economy] [ interest rates+] 
to plunge (to sth) 猛然跌入(某状态)

8.vi.[bird+] 
俯冲

to take the plunge
 [fig] 采取断然行动
to plunge (o.s.)/be plunged into sth
全身心投入某事