celeriacPronunciation: /sɪˈlɛrɪak/Translate celeriac | into Italian Definition of celeriac noun [mass noun] celery of a variety which forms a large swollen turnip-like root which can be eaten cooked or raw. Origin: mid 18th century: from celery + an arbitrary use of -acceleriac in other Oxford dictionaries Definition of celeriac in the US English dictionary