noun

• An almost transparent aquatic animal; any one of the acalephs, especially one of the larger species, having a jellylike appearance.
• A cnidarian, a member of the phylum Cnidaria.
• A scyphozoan, a member of the class Scyphozoa (the true jellies).
• A ctenophore, a member of the phylum Ctenophora (the comb jellies).
• A sudoku technique involving possible cell locations for a digit, or pair, or triple, in uniquely four rows and four columns only. This allows for the elimination of candidates around the grid.