The Kanji: 凸 (Totsu / Deki)
The kanji 凸 (read as totsu or deki) is a pictographic character that visually represents a "convex" shape. It means "to protrude," "to bulge out," or "to be uneven." Its mirror counterpart is 凹 (concave). Together, they form a pair describing opposing surface profiles.
Common Words & Example Sentences
1. 凸凹 (dekoboko)
Meaning: Unevenness; roughness; bumpy.
Example Sentence: この道は凸凹していて歩きにくい。
(Kono michi wa dekoboko shite ite aruki nikui.)
"This road is bumpy and hard to walk on."
2. 凸面 (totsumen)
Meaning: Convex surface.
Example Sentence: ルーペは凸面レンズを使っている。
(Rūpe wa totsumen renzu o tsukatte iru.)
"A magnifying glass uses a convex lens."
3. 凸版 (toppan)
Meaning: Letterpress; relief printing.
Example Sentence: 凸版印刷は歴史のある技術だ。
(Toppan insatsu wa rekishi no aru gjutsu da.)
"Relief printing is a technique with a long history."
In summary, 凸 is a straightforward, shape-based kanji for anything that protrudes or is convex. It is most commonly used with its opposite, 凹, in the word 凸凹 to describe physical unevenness, and also appears in technical terms like 凸面レンズ (convex lens) and 凸版 (relief printing).