减弱或消失to fade

• 她的笑容收敛了。

  Her smile faded.

• 她想到这一层，就收敛了笑容。

  When she thought about that aspect her smile faded.

• 夕阳已经收敛了余晖。

  The last rays of the setting sun have faded.

约束言行to restrain

• 现在他的态度收敛了一些。

  Now he is a bit more restrained.

• 经过批评以后，他的行为收敛了一些。

  After receiving some criticism he acted with more restraint.

【数】convergence

• 收敛级数

  convergent series

• 平均收敛

  mean convergence

【医】astringent