An agreement, either tacit or explicit, to disclose nothing about an individual or situation. The term nearly always refers to disclosing something unfavorable, or even criminal. For example, physicians often have been accused of protecting an incompetent member of their profession by keeping quiet. Dating from the late nineteenth century, the term at first was used by individuals complaining of lack of attention. The poet Lewis Morris reportedly complained to Oscar Wilde that a conspiracy of silence prevented his works from being reviewed and asked what he should do, whereupon Wilde replied, “Join it.”

Speechlessness that speaks louder than speech. “Often there is eloquence in a silent look,” wrote the Roman poet Ovid in his Artis Amatoriae (The Art of Love), a three-volume how-to text for lovers (ca. 1 b.c.). Cicero, Tasso, and La Rochefoucauld were among the many who echoed the sentiment, although not all in the service of love. In English, the playwright William Congreve said (Old Batchelour, 1693, 2:9), “Even silence may be eloquent in love.” It was already a cliché by the time Thomas Carlyle (On Heroes and Hero-Worship, 1840) wrote, “Silence is more eloquent than words.” A newer synonym, dating from the second half of the 1900s and rapidly becoming a cliché, is deafening silence. It is used especially to refer to a refusal to reply or to make a comment. The Times had it on Aug. 28, 1985: “Conservative and Labour MPS [Members of Parliament] have complained of a ‘deafening silence’ over the affair.” See also actions speak louder than words.

To keep quiet is a great virtue. This expression is the second half of an old proverb: “Speech is silvern and silence is golden.” It began to be much repeated in the nineteenth century. Thomas Carlyle referred to it as a Swiss proverb in Sartor Resartus (1831). A number of variants came later, among them Ogden Nash’s “Silence is golden, but sometimes invisibility is golder” (I Never Even Suggested It, 1938).