之间
zhījiān · HSK 4
between
↔️ 之间 = 之 (of) + 间 (gap/space) — the gap of, i.e. between
间 splits into 门 (door) + 日 (sun) — sun showing through a door gap, the original sense of 'interval/space between'. 之 is a classical particle meaning 'of', so 之间 literally reads as 'the space of', used for 'between/among'.
之 — foot 止 above ground line 一
Originally a pictograph of a foot (止) stepping forward from a baseline, meaning 'to go' or 'to proceed'. Over time the concrete 'going' sense faded, and 之 was borrowed as a grammatical particle marking possession ('of') or as a pronoun ('it'), which became its dominant use in Classical Chinese.
间 — gate 門 + sun 日 (originally moon 月)
Originally written 閒, showing the moon 月 shining through a gate 門 — the gap or space between the doors. The moon was later replaced by 日 (sun), giving the modern 间. The core meaning 'space/interval between' extended to time intervals, rooms, and the measure word for buildings.