fine rain falling after sunset from a sky in which no clouds are visible.
Origin: 1865–70; < F serein, MF serain evening, nightfall < VL *sērānum, equiv. to L sēr(um) a late hour (neut. of sērus late) + -ānum, neut. of -ānus-an; cf. obs. E serene < MF
[suh-ran] 
