1.
hammer
A tool with a heavy metal head used for hitting nails.
2.
person who can't swim
Colloquial term for someone who sinks like a hammer in water.
金槌 has two meanings: a hammer (tool) and a person who can't swim.
SENSE 1 - HAMMER:
SENSE 2 - NON-SWIMMER (COLLOQUIAL):
WHY THIS MEANING?
A metal hammer sinks immediately in water - just like someone who can't swim!
WORD FORMATION:
金 (metal) + 槌 (hammer)
ALTERNATIVE WORDS:
- ハンマー: hammer (loanword)
- 木槌: wooden mallet