In the production of rum: the lees or dregs from the fermentation of a batch of cane juice or molasses, which contains active yeasts and is typically reserved and left to ferment in a vat or pit before being used to start the fermentation of fresh batches. In early use also: †refuse or dregs from the process of sugar production, used in the fermentation of rum (obsolete).
The use of dunder to start fermentation is characteristically associated with Jamaican rum.
Late 18th century; earliest use found in Edward Long (1734–1813), planter and commentator on Jamaican affairs. Apparently irregularly from Spanish redundar to overflow, with loss of the initial syllable and retention of the Spanish infinitive ending.
1A loud, reverberating noise; a loud rumble.
2A resounding, heavy blow.
Late 18th century. From dunder.
1To make a loud, deep resounding noise; to reverberate, rumble.
2To knock, bang, or fall on something with a loud, resounding noise, especially to knock loudly and repeatedly on a door. Followed by a prepositional phrase, especially with on or at.
Early 18th century; earliest use found in Battle of Harlaw. Probably from a form in a Scandinavian language from Middle Low German donnern, donren, dondern.