1A hollow, cylindrical object; a pipe, tube, or cylinder.
紙の筒に布を巻いて保管した。
I wrapped the cloth around a paper tube for storage.
排水用の金属の筒が壊れているので交換が必要だ。
The metal drainage tube is broken and needs to be replaced.
ペン立ては小さな筒の集合のようだ。
A pen holder is like a collection of small tubes.
2The barrel of a gun or cannon — the cylindrical part through which a projectile is fired.
猟が終わったら銃の筒をきれいに掃除する。
After hunting I clean the gun barrel thoroughly.
3An older or literary use meaning a gun or cannon (the whole weapon), found in historical or literary contexts.
昔の文献には戦で多くの筒が使われたと書かれている。
Old documents say many guns/cannons were used in battles.
4A cylindrical lining or curb used inside a well (the well lining or curb).
古い井戸の筒が土で埋まっていたので修理した。
The old well lining was filled with earth, so we repaired it.