限界
げんかい · genkai · JLPT N3 · noun
limit
🚧 限 limit + 界 boundary = the line you cannot go past
限 means to restrict, as in 制限 (restriction). 界 means a boundary or world, as in 世界 (world). Put them together and you get the edge of what is possible. It is common in 限界です, meaning I'm at my limit.
限 — mound radical 阝 + 艮 (phonetic)
限 combines the 阝 (mound/hill) radical on the left with 艮 on the right, which provides the sound. The mound element suggests a boundary or barrier formed by terrain, and the character came to mean 'limit' or 'boundary' — the edge one cannot cross.
界 — field 田 + scope 介
界 combines 田 (field) as the semantic component with 介 (jiè) as the phonetic. The original sense referred to boundaries between fields, then broadened to any border, limit, or realm — yielding modern meanings like 'world' (世界) and 'boundary' (边界).