所长
suǒzhǎng · HSK 3
head of an institute/etc.
🏛️ 所 (place) + 长 (chief) = chief of a place/institute
所 means a place or institute (office, station, research center); 长 here is zhǎng meaning chief or head. Together: the head of an institute. Same 长 as in 校长 (school principal) and 班长 (class leader).
所 — door 戶 (left) + axe 斤 (right)
Originally a sound: an axe (斤) chopping wood near a door (戶), with 戶 also hinting at the pronunciation. Over time it was borrowed to mean 'place' or 'location,' and later became a grammatical particle nominalizing verbs ('that which…'). The concrete 'chopping' sense faded entirely.
长 — pictograph of long-haired person with cane
Originally a pictograph showing a person with long, flowing hair leaning on a cane, representing an elder. The meaning extended from 'long hair' to 'long' in general, and also to 'elder' or 'to grow' (read zhǎng). The modern form 长 is a simplification of the traditional 長.