下旬
xià xún · HSK 7
last third of the month
📅 下 lower + 旬 ten-day period = the lower (last) ten-day stretch of a month
下 — horizontal line 一 + mark below
下 is an indicative character: a long horizontal line represents a reference level, and a shorter stroke placed beneath it points to the area below. The original meaning 'below, down' comes directly from this spatial diagram, and it later extended to verbs like 'descend' and 'lower'.