1. a small freshwater or marine fish with sharp spines on its back

Examples

• The three-spined stickleback is common in European ponds.
• Sticklebacks build elaborate nests during breeding season.
• The male stickleback guards his territory aggressively.
• We caught several sticklebacks in the shallow creek.
• The stickleback’s spines help protect it from predators.
• Marine sticklebacks can tolerate both salt and fresh water.