Definition of "jellyfish"

An almost transparent aquatic animal; any one of the acalephs, especially one of the larger species, having a jellylike appearance.

1. A cnidarian, a member of the phylum Cnidaria.

   1. A scyphozoan, a member of the class Scyphozoa (the true jellies).  examples

2. A ctenophore, a member of the phylum Ctenophora (the comb jellies).  examples

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.  examples