赤紙

(historical) red paper used as a charm or ward against pox (usually smallpox, also the great pox or syphilis), and pasted on the frame of oil lamps or on 仁王 (Niō, “Nio”) statues

a slip of red paper attached to a letter or other document to indicate urgency

alternative name for 赤新聞 (aka shinbun, “scandal rag, gutter press, yellow journalism”)

(informal) draft card (from the color of the paper stock used for these)

(informal) a label or sticker indicating that something is under seizure or garnishment

Used other than figuratively or idiomatically: see 赤, 紙. (red paper)