brainchild
n. countable B2 Upper Intermediate US //ˈbɹeɪnˌtʃaɪɫd// UK //bɹˈeɪntʃaɪld// brain·child
n. an idea or a project that someone has created or thought of. It is often used to describe something that took a lot of time and effort to make.
n. an idea, invention, or project that has been conceived or created by a specific person. Often carries a slightly informal or affectionate tone when referring to a complex or ambitious undertaking.
The new app is the brainchild of a small team of students.
The community garden was the brainchild of a local teacher who wanted to bring people together.
While the initial concept was a simple sketch, the final skyscraper proved to be the brainchild of an architect whose vision had been shaped by years of studying urban density.
From brain + child.