Celery is a member of the Apiaceae family, which also includes carrots, parsley, and fennel. The word celery derives from the French céleri, which in turn comes from the Latin celeris (meaning swift).
In English, there are two common ways to say celery. The first is simply celery, which is the most direct translation from the French céleri. The second way is to use the word celeriac, which is derived from the Latin root celer (meaning swift). This word is less commonly used in English, but it is still understood by many people.