This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
歮 is a rare character formed by tripling the 止 component. Its exact historical origin and original meaning are uncertain.
Three 止 (stop) components stacked together suggest something like 'repeated stopping' or 'stagnation', but the actual meaning is unclear.
For シュウ, imagine a crowd of people all stopping at once, making a 'shoo' sound as they halt: shoo -> シュウ, and the triple 止 reinforces the idea of stopping.