凹凸

1. Origins, structure, and basic meaning

• Structure: Written 凹凸 and read おうとつ, it denotes alternating hollows and projections that make a surface uneven.
• Basic usage: It appears in old stone paving and on a board smoothed with sandpaper.

2. Common pitfalls and similar expressions

• Both depressions and bumps
  • The term combines low and raised areas rather than naming only one type of defect.