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.
One who moves in a stealthy or furtive way; one who comes or goes while trying to avoid detection.
One who stays where they cannot be seen (often in a cowardly way or with the intent of doing harm).
One who avoids an obligation or responsibility.