From French 'Nanette', diminutive of Anne, meaning grace, popularized in 1940s-50s America.
Nicknames
nan · nannie
Vibe
strong
How it ages.
Nancy peaked sharply in 1950s-60s America and has declined substantially, now decidedly vintage.
The cultural moment.
North America experienced Nancy as top-10 name in 1950s-60s, then consistent steep decline from 1970 onward, now strongly associated with vintage era. Currently ranks #70 in the UK.
Other Hebrew via French names with similar texture: