Phalanx/ˈfeɪlæŋks/ Definition 1 of 3Pro Tip 1/3Unity of Movement It emphasizes coordinated action, often representing solidarity or discipline. Protesters marched in a phalanx, undeterred by the barriers. Pro Tip 2/3Metaphorical Use It's sometimes used figuratively to describe an organized approach to a challenge. The developers stood in a phalanx against software bugs. Pro Tip 3/3Impenetrability The word suggests a group so closely formed that it's hard to break through. The security guards formed an impenetrable phalanx at the entrance.