This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
磓 combines 石 (stone) with 追 (pursue, follow). The exact historical development is uncertain, but it likely relates to stone or rock in some context.
A stone 石 being followed 追, perhaps like a rolling stone chasing something, but its meaning is unclear.
For タイ, imagine a stone tied to a rope: tie -> タイ, and the stone follows along.