Ajowan; botanical name of Trachyspermum copticum. Also known as ajwain or ajowan caraway, carom seeds, or mistakenly as bishop's weed, is an uncommon spice except in certain areas of Asia and Africa.
Raw ajwain smells almost exactly like thyme because it also contains thymol, but is more aromatic and less subtle in taste, as well as slightly bitter and pungent. It tastes like thyme or caraway, only stronger. Even a small amount of raw ajwain will completely dominate the flavour of a dish.
In Indian cuisine, ajwain is almost never used raw, but either dry-roasted or fried in ghee or oil. This develops a much more subtle and complex aroma, somewhat similar to caraway but "brighter". Among other things, it is used for making a type of paratha, called 'ajwain ka paratha'.
Ajwain originated in the Middle East, possibly in Egypt. It is now primarily grown and used in the Indian Subcontinent, but also in Iran, Egypt and Afghanistan. It is sometimes used as an ingredient in berbere, a spice mixture favored in Eritrea and Ethiopia.