Correct

咝

/ sī / 
Strokes

Definition

(onom.) to hiss/to whistle/to whiz/to fizz

Example

As an Onomatope

whistle; hiss

1
Lúzi
炉子
shàng
上
de
的
shuǐhú
水壶
fāchū
发出
sīsī
咝咝
de
的
shēngyīn
声音
  
。

The kettle was whistling on the stove.