(onomatopoeia) The hiss of a snake or other reptile.

(Philippines) Social Security System / (US) Selective Service System

(astronomy) Initialism of super soft source. / (medicine) Initialism of sick sinus syndrome. / (medicine) Initialism of subclavian steal syndrome. / (slang) Initialism of shit, shower, shave.

Initialism of site of special scientific interest.

Alternative form of shh

(medicine) Initialism of staphylococcal scalded skin syndrome. / Initialism of Secondary Security Screening Selection.

plural of SSSI