縦

1. Origins, structure, and basic meaning

• Structure: 縦 (たて) is the vertical or lengthwise direction.
• Basic usage: 紙を縦に折る modifies the folding direction; 箱の縦の長さ names a lengthwise dimension.

2. Common pitfalls and similar expressions

• Directional 縦に and dimensional 縦の長さ
  • Use に for how an action is oriented and の to connect the axis to a measured length.