凸 (readings: とつ, でこ; Japanese kanji) means “Convex / Beetle Brow / Uneven”. It is a Jōyō kanji taught in Japanese secondary school (junior & senior high) — the 高手 · Master tier beyond the grade 1–6 Kyōiku set, and appears in words such as 凸凹 (uneven).
What does 凸 mean?