Definition of "SF"

(fiction) Initialism of science fiction or speculative fiction, often used to avoid having to choose between the two.  examples

Initialism of square feet.  examples

Initialism of spontaneous fission.  examples

(basketball) Initialism of small forward.  examples

(sports) Abbreviation of semifinal.  examples

Initialism of San Francisco.  examples

(Ireland, UK politics) Initialism of Sinn Féin; an Irish political party.  examples

(video games) Initialism of Street Fighter.  examples

(motor racing) Initialism of Super Formula.  examples

(in personal ads) Initialism of smoker-friendly: not objecting to people who smoke tobacco  examples