Coriander is a cooking plant. The fresh green leaves have a strong smell: a lot of people love them on soup and noodles, and some people say they taste like soap. That is a real difference in how tongues read the plant, not just being fussy. The little round seeds are warmer and a bit lemony; we use them whole or ground. In British English, coriander often means the whole plant — leaves and seeds. In American English, people usually call the leaves cilantro and keep coriander for the seeds. So the same bunch of green on a Taiwanese stall might be “coriander” to a British speaker and “cilantro” to an American one. The word came through French and Latin from Greek; nobody is sure where the Greek word began. Cilantro is the same plant by another path, through Spanish.