something that needs careful thought; something questionable
Used when a matter requires careful consideration or when its appropriateness is in doubt. Often appears in phrases like 考え物だ.
That plan really needs careful thought.
Accepting it too easily is questionable.
Less common; refers to a brain-teaser or conundrum. Often replaced by パズル or なぞなぞ in modern speech.
This puzzle is quite hard to solve.