sealer1 Syllabification: (seal·er)Pronunciation: /ˈsēlər/Definition of sealer noun 1a device or substance used to seal something, especially with a hermetic or an impervious seal. 2 (also sealer jar) Canadian a jar with a hermetic seal designed to preserve food such as fruit, pickles, and jams. sealer in other Oxford dictionaries Definition of sealer in the British & World English dictionary