noun, na-adjective
indiscretion; bad idea; thoughtlessness
Rare term for a lapse in judgment, a foolish or ill-considered notion. Often used in set phrases like 不了見を起こす (to get a bad idea).
若気の至りで、つい不了見を起こしてしまった。
In the folly of youth, I ended up having an indiscreet idea.
そんな不了見
You should abandon such a thoughtless plan right away.
不心得 also means indiscretion or imprudence, but is more common and often implies moral wrongdoing, while 不了見 is rarer and focuses on poor judgment or a bad idea.
無分別 means thoughtlessness or imprudence, and is more widely used than 不了見. 不了見 carries a nuance of a specific indiscreet notion or plan.
The word is composed of 不 (not) and 了見 (idea, thought, discretion). 了見 itself originally meant 'to understand clearly' and later came to mean 'idea' or 'discretion'. The exact historical derivation is uncertain, but the compound 不了見 follows a common pattern of negating a noun to indicate a lack of that quality.