Late Old English rudig, from the base of archaic rud 'red colour'; related to red.

• red from Old English:

  An Old English word which shares an ancient root with Latin rufus, Greek eruthros, and Sanskrit rudhira ‘red’. The colour red has traditionally been associated with radical political views, and from the 19th century particularly Communists. During the Cold War, when Americans feared reds under the bed or Communist sympathizers, the expression better dead than red was used to mean that the prospect of nuclear annihilation was preferable to that of a Communist society. The slogan was reversed by nuclear disarmament campaigners of the late 1950s as ‘better red than dead’. Something involving savage or merciless competition might be described as red in tooth and claw. The phrase came from Lord Tennyson's poem ‘In Memoriam’ (1854): ‘Nature, red in tooth and claw’. In Church calendars a saint's day or Church festival was distinguished by being written in red letters. This gives us a red letter day (early 18th century) for a pleasantly memorable, fortunate, or happy day. A less cheering use of red ink was customarily made to enter debit items and balances in accounts —which gives us in the red (early 20th century) to mean in debt or overdrawn.

  The colour red is supposed to provoke a bull, and is the colour of the cape used by matadors in bullfighting. From this we say that something will be like a red rag to a bull (late 19th century). A red herring is something, especially a clue, which misleads or distracts you. Red herrings have been around since the 15th century and got their colour from being heavily smoked to preserve them. The pungent scent was formerly used to lay a trail when training hounds to follow a scent. The red light district of a town is one with a lot of businesses concerned with sex. The phrase is from the red light traditionally used as the sign of a brothel. See also paint. People have been complaining about red tape, or excessive bureaucracy, since the 1730s. Real red or pinkish-red tape is used to bind together legal and official documents. Americans sometimes talk of not having a red cent to their name. Red got attached to the cent in the mid 19th century and refers to the colour of the copper used to make the one cent coin. Ruddy is from Old English rud, a variant form of ‘red’. The word's use as a euphemism for bloody dates from the early 20th century.