1.
in use, occupied
A status indicator showing that something (such as a restroom, meeting room, or equipment) is currently being used.
Related Words
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故障中 (out of order)
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営業中 (open for business)
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清掃中 (being cleaned)
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空き (vacant, available)
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空室 (vacant, available)
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稼働中 (in operation)
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通話中 (on a call)