superficial knowledge; smattering
Refers to shallow, half-baked knowledge. Often used critically to describe someone who knows just enough to sound informed but lacks real depth.
His knowledge of economics is superficial, and he quickly shows his ignorance in front of experts.
半可通なアドバイスはかえって危険だ。
Half-baked advice can be more dangerous than none at all.
person with superficial knowledge; dilettante; pretentious know-it-all
A person who has only a smattering of knowledge but acts as if they are an expert. Carries a negative, mocking tone.
あの人は半可通だから、話半分に聞いたほうがいい。
That person is a dilettante, so you'd better take what they say with a grain of salt.
半可通ほど始末に負えないものはない。
There's nothing more troublesome than a person with superficial knowledge.
生半可 is an adjective meaning half-hearted or superficial, often used for skills or efforts, whereas 半可通 is a noun/adjective focused on knowledge and the person who has it.
Formed from 半可 “incomplete or superficial knowledge” and 通 “connoisseur, expert,” originally denoting someone who pretends to expertise on the basis of partial understanding.