(automotive) Initialism of supplemental restraint system or secondary restraint system (car airbags). / (medicine) Initialism of sex reassignment surgery.

(Internet slang, text messaging) Abbreviation of serious.

(Internet slang, tone indicator) Denotes that the preceding statement is said in a serious manner.

(UK) Abbreviation of senior; A title used after a father's name when his son is given the same name.

Abbreviation of sister; A title for a nun. / Abbreviation of surveyor, adopted by The Hong Kong Institute of Surveyors as a title of its Corporate Members.

Abbreviation of senior. A title used after a father's name when his son is given the same name.

Abbreviation of Sister. The tile for religious sisters in Christianity.

Initialism of Slovak Republic. / (UK, rail transport) Initialism of Southern Railway. / Initialism of Saudi riyal.

(uncountable) Initialism of semen retention. / (uncountable) Initialism of special relativity. / (uncountable) Initialism of speculative realism. / (countable) Initialism of speculative realist.

(Internet slang) Something that is serious, important, formidable, etc., or is treated as such.