This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 棽 is uncertain. It visually combines 林 (forest) and 今 (now), but the original semantic or phonetic role of these components is unclear.
Since the meaning is unclear, focus on the shape: a forest 林 above 今 (now). Picture a dense forest that suddenly appears now, but its purpose is unknown.
For チン, imagine a rare forest where a chinchilla (chin -> チン) hides under the trees 林 right now 今. The chinchilla's name cues the reading.
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