noun
well curb; well kerb
The wooden or stone frame around the top of a well. Often square in traditional Japanese wells.
古い庭に石の井筒が残っている。
A stone well curb remains in the old garden.
noun
family crest with a well curb design
A kamon (family crest) pattern based on the shape of a square wooden well curb. Used as a heraldic motif.
この家の家紋は井筒です。
This family's crest is the well curb design.