family atmosphere; homey feel
Describes a warm, welcoming, and informal environment reminiscent of a close-knit family. Often used for workplaces, restaurants, or gatherings.
This café has a family atmosphere and is very relaxing.
The company year-end party was held in a homey atmosphere.
アットホーム is a loanword often used similarly to describe a cozy, home-like atmosphere, but 家族的な雰囲気 explicitly evokes the feeling of being with family.
A phrase composed of 家族的 (family-like) + な (attributive) + 雰囲気 (atmosphere). The exact origin is straightforward; it is a common descriptive expression.