Ajwain, also known as ajowan caraway, carom seeds or mistakenly as bishop's weed, is an uncommon spice except in certain areas of Asia. The greyish-green seeds are striped and curved (similar to cumin or caraway seeds in appearance), often with a fine silk stalk attached. They are usually sold whole.

Raw ajwain smells almost exactly like thyme, but is more aromatic and stronger in taste, as well as slightly bitter and pungent. Even 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'.

The seeds are often chewed on their own for medicinal value, tasting bitingly hot and bitter, leaving the tongue numb for a while.