Definition of happy family in English:
happy family
noun ˌhapi ˈfam(ɪ)liˌhapi ˈfam(ə)li
1A family living together harmoniously (frequently as a conventional description). Also figurative: a group characterized by high morale, team spirit, etc.
2A collection of diverse animals (or fish) living together in harmony in one cage (or tank, etc.), especially one exhibited as a curiosity.
3In plural A children's card game played with a pack of special cards, each card depicting on its face a member of a ‘family’ of four.
4Australian. Either of two songbirds that typically occur in small groups: the apostlebird or grey jumper, Struthidea cinerea (family Corcoracidae), and the grey-crowned babbler, Pomatostomus temporalis (family Pomatostomidae). In later use also: any Australasian babbler of the family Pomatostomidae.
Phrases
one (also a) (great) big happy family
: a group of people who coexist happily and harmoniously and work towards the same goals (sometimes ironic); also in extended use.
: to behave like a harmonious, contented family, especially only as a pretence; also in extended use.
Origin
Mid 16th century. From happy + family.