scaffold, cleat, frame, jetty, bolt (door)
桟 centers on a temporary or supporting wooden structure: a scaffold, a frame, a jetty, or a cleat. The bolt sense extends this idea to a wooden bar used to secure a door.
桟 is the modern simplified form of 棧. The older form combines 木 (wood) with 戔, which likely contributed the sound and the idea of a wooden structure. The modern right side 㦮 is a simplified version of 戔.
The left side is wood 木, and the right side 㦮 looks like stacked planks. Picture a wooden scaffold or frame built from planks.
For サン, imagine the sun shining on a wooden scaffold: sun -> サン, and the scaffold casts a shadow.
wharf; bridge; jetty; pier
frame (i.e. of a sliding door)
sheathing (under thatched roofing)
dress circle (of a theatre); (first) balcony; box
being kept uninformed; being cut off; out of the loop
gallery (in a theatre); upper gallery; cheap seats; nosebleed section; the gods
to nail a crosspiece (to)
straw lid covering either end of a rice container
panelled wooden door
batten door; battened door; ledged door; strong door with crosspieces placed on the reverse side
pantile
striped cotton fabric imported from Sao Tome, also copied in Japan
sheathing (under thatched roofing)
plank path (on a steep mountainside, cliff face, etc.); walkway
horizontal bar; crosspiece; crossbar; crossrail; rung (of a ladder)
floating pier
window frame; window sill
frame of a shoji (paper sliding-door)