open, through

甬 is composed of 用(use) and the variant of 厶(private). 用 is the picture of bucket, while 厶 is the picture of a lasso, so 甬 depicts a bucket with a lasso as handle. On the other hand, a bucket is hollow, so 甬 also has the meaning of going through. 甬 is the origin of both 通 and 桶, but now we seldom use it.