The noun brainchild refers to an original idea, creative thought, or invention attributed to a person or group. Think of a brainchild as a figurative child birthed by a brain. That’s the conventional definition of the word, anyway, and has been since it was coined in the late 19th century.
Yet brainchild is occasionally used to refer to a person who has good ideas or a person or group who has an idea or creates something. This sense is not common enough to have gained acceptance, and it is still not listed in any of the several dictionaries we checked. Examples are easily found, though:
The Center for Public History and Digital Humanities at Cleveland State University is the brainchild behind the app. [Cleve Scene]
She is the brainchild of this innovative workshop. [Pune Mirror]
He is the brainchild behind a series of workshops being held in Durham. [Journal Live]
But the original sense still prevails by a large margin, and some English speakers might be confused by the newer use of the word. Here are a few examples of the word put to use in its original sense:
It began life 30 years ago as the brainchild of disillusioned nuclear power engineer and yesterday established its first business arm in the US. [Herald Scotland]
The group was the brainchild of Rachel Doll O’Mahoney, Seattle U’s Campus Minister for Faith Formation. [Seattle University Spectator]
The inventive ad is the brainchild of advertising agency DCS Brazil. [Tecca]