其间
qí jiān · HSK 7
in the meantime
⏳ 其 = that + 间 = between; so 'that between' = within that interval
间 also shows up in 时间 (time) and 中间 (middle), always pointing at a gap or interval. 其 means that/those, so 其间 is literally the span sitting inside that stretch of time.
其 — top 八 + winnowing basket 其 (originally 箕)
Originally a pictograph of a bamboo winnowing basket, now written 箕 with the bamboo radical added on top. The original form 其 was borrowed phonetically to write the pronoun and particle meaning 'his/her/its' or 'that.' This loan use became dominant, so a new character 箕 was created for the basket meaning.
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.