月末
げつまつ · getsumatsu · JLPT N2 · noun
calendar month
📅 月 (month) + 末 (end, tip) = month + end = the end of the month
月 — pictograph of crescent moon
月 is a pictograph of a crescent moon, chosen over a full circle to distinguish it from 日 (sun). The inner strokes originally depicted the moon's shadow or markings. As a radical it often relates to the moon, time, or (via a lookalike form of 肉 'flesh') body parts.
末 — tree 木 with extended top stroke marking the tip
末 is an indicative character: it shows the tree 木 with an emphasized horizontal line near the top to point at the treetop, the 'tip' or 'end' of the branches. From this concrete sense it extended to mean 'end,' 'final,' or 'minor/trivial' (as opposed to the root 本).