或
ある · aru · JLPT N3 · na-adj
a certain...
或 = 戈 halberd guarding 口 an unnamed plot of land → some place, a certain...
或 was the original form of 國 (country) and 域 (region): a halberd 戈 guarding a walled area 口. It was later borrowed to mean some or a certain, and the land meaning moved to 國. In Japanese 或る (aru) comes before a noun: 或る日 = one day.
或 — 戈 dagger-axe + 口 mouth/area + 一 boundary line
或 originally depicted a dagger-axe (戈) guarding a bounded territory (口 with 一), meaning 'country' or 'domain' — the ancestor of 國/国. Over time it was borrowed for the abstract sense 'perhaps, maybe, or,' so a new 囗 enclosure was added around it to write the original 'country' meaning.