Answer:

siss

Answer	Crossword Clue
SISS	Deflation sound
SISS	k.d. lang and The ... Boom Bang
SISS	Greeting for the villain

SISS	Puncture sound
SISS	Hiss.
SISS	Jap sound indicating politeness.
SISS	Noise made by water dropped on a hot store.
SISS	Sibilant sound.
SISS	Sound of escaping steam.
SISS	Sound of a boiling kettle.
SISS	Fie!

SISS	Hissing sound.
SISS	Sibilant interjection.
SISS	Sizzle.
SISS	Steamy sound.
SISS	Sound from a pressure cooker.
SISS	Make a hissing sound.
SISS	Sibilant sound of derision
SISS	Before "boom, bah"

SISS	Snaky sound
SISS	Hissing sound
SISS	Sibilant sound
SISS	Sound of a reptile or steam
SISS	Radiator sound
SISS	Sound of escaping steam
SISS	Leaking radiator's sound
SISS	Snake sound

SISS	Leaky noise
SISS	Make a sibilant sound