1.
wavy line; squiggly line
A line that curves up and down in a wave-like pattern. Used in documents, diagrams, and proofreading marks.
Usage
In graphs and charts, a 波線 on an axis indicates that part of the scale has been omitted. In proofreading and note-taking, wavy underlines are used to highlight important passages. The tilde character (~) is also sometimes called 波線.