The kanji 凸凸 represents a raised or protruding shape, like a bump or a projection. It signifies something that is convex or bulges outward.

・On-yomi (音読み): ・ト (to) ・Kun-yomi (訓読み): ・でこ (deko) – This is often used for "forehead" or "bump."

⚫︎凸凹 (でこぼこ) Translation: Uneven; bumpy; rough. ⚫︎凸レンズ (とつレンズ) Translation: Convex lens. ⚫︎凸版 (とっぱん) Translation: Relief printing (printing from a raised surface).

The kanji 凸凸 is a pictograph. It depicts the shape of something protruding or projecting outwards. The shape itself is the origin of the character, visually representing a bump or a raised area. Over time, the form has simplified, but the core meaning remains.