Variant spelling of Shelley, from Old English scealf-leah (shelf meadow); the -y spelling is less literary than the -ey form but equally tied to the mid-20th century American feminine naming wave.
Nicknames
shell
Vibe
gentle
How it ages.
The -y spelling dates it slightly more than the -ey form; both feel firmly mid-century.
The cultural moment.
Common in the US and Australia from the 1950s through the 1970s; declining steadily since.