Rosemary (Rosmarinus officinalis) is a small perennial evergreen shrub of the mint family (Laminaceae, or Labiatae) whose leaves are used to flavor foods. Rosemary leaves have a tealike fragrance and a pungent, slightly bitter taste. They are generally used sparingly, dried or fresh, to season foods such as lamb, duck, chicken, sausages, seafood, stuffings, stews, soups, potatoes, tomatoes, turnips, other vegetables, and beverages. Whole sprigs are removed before food is served because of their powerful taste.

Rosemary has been used extensively since 500 b.c. In ancient Greece, it was recognized for its alleged ability to strengthen the brain and memory. Greek students braided rosemary into their hair to help them with their exams. Rosemary's name joins two Latin words meaning "dew of the sea" because it thrives where fog and salt spray meet. It is also known as the herb of remembrance. In Hamlet, Ophelia said, "There's rosemary, that's for remembrance." Even today, it is placed on the graves of English heroes. In one legend, rosemary is used to waken Sleeping Beauty; in another, fairies take the form of snakes and lie among the rosemary. Rosemary was used by the American colonists to scent soap. Today, its fragrant oil is an ingredient in numerous toiletry products and in vermouth. Native to the Mediterranean region, it has been naturalized throughout Europe and temperate America and is widely grown in gardens in the warmer parts of the U.S. and in Great Britain, where an old garden legend reads "where rosemary thrives the mistress is master."

The rosemary bush has a main stem usually around 3 feet (1 metre) but sometimes up to 7 ft tall. The linear leaves are about 0.4 inch (1 centimetre) long and resemble curved pine needles, which are dark green and shiny above, white beneath, and with margins rolled back onto the under face. The flowers are bluish, in small axillary clusters. Bees are particularly fond of rosemary.

The essential oil content is from 0.3 to 2 percent, and it is obtained by distillation. Its principal component is borneol.