Used after a pause for thought to introduce a new topic, question or story, or a new thought or question in continuation of an existing topic.

Abbreviation of someone.

(music) A syllable used in solfège to represent the fifth note of a major scale.

(foods) A type of dairy product, made especially in Japan between the seventh and 10th centuries, by reducing milk by boiling it.

Initialism of significant other. / (sports) Initialism of shut out. / (sports) Initialism of shootout. / (baseball) Initialism of strike out. / (logic, computer science) Initialism of second-order logic.

Initialism of someone.

The conventional Morse code call made by a ship in distress.

Initialism of Secretary of State. / Initialism of special order sale.

(colloquial) Initialism of slip on show: a warning to a woman that the underwear she has on can be seen.

(games) A children's game in which players take turns to place S's and O's on a grid, collecting points by creating an "SOS" sequence.