noun
Historical term for glass or glassware, especially from the Edo period onward. Now largely replaced by ガラス, but still encountered in historical or literary contexts.
from Dutch diamant
江戸時代には、ギヤマンは貴重な輸入品だった。
In the Edo period, giyaman was a precious imported item.
noun
Obsolete original meaning from Dutch 'diamant'. The modern word for diamond is ダイヤモンド.
「ギヤマン」はもともとダイヤモンドを指したが、今は使われない。
Giyaman originally meant diamond, but it is no longer used that way.