This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
薝 is a phono-semantic compound: 艹 (plant) combined with 詹, which likely provides the sound. The exact historical development is uncertain.
The top 艹 suggests a plant, and the bottom 詹 looks complex. Imagine a mysterious, unnamed plant with tangled leaves and stems.
For セン, picture a thousand (千, せん) tiny leaves on this unknown plant: 千 -> セン, and the plant is covered in them.
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