(Internet slang) Abbreviation of have fun.

(electronics) Initialism of high frequency.

(finance) Initialism of high-frequency.

(text messaging) Abbreviation of have fun.

(organic chemistry) Initialism of hydrofluorocarbon. / (electrochemistry) Initialism of hydrogen fuel cell.

(uncountable) Abbreviation of high-functioning autism. / (chemistry, countable) Abbreviation of hydrofluoroalkane.

plural of HFC

Initialism of high fructose corn syrup.

(informal) Hot from far away (but ugly up close)

(virology) Initialism of hepatitis F virus. / (virology) Initialism of human foamy virus. / (medicine) Abbreviation of high frequency ventilation.