Modifiers matching boundary:

• structural,
• real,
• physical,
• natural,
• convenient,
• moving,
• cultural,
• syntactic,
• geopolitical,
• significant,
• governing,
• solid,
• atmospheric,
• hydraulic,
• vertical,
• distinct,
• political,
• semitransparent,
• jurisdictional,
• hierarchical,
• geographical,
• logical,
• nearby,
• simple,
• smooth,
• nonconducting,
• complex,
• spatial,
• hexagonal,
• ecological,
• curved,
• legal,
• sharp,
• visual,
• internal,
• biological,
• external,
• front,
• spherical,
• single,
• oceanic,
• rigid,
• critical,
• clear,
• smaller,
• irregular,
• administrative,
• outer,
• permanent,
• horizontal,
• crystalline,
• static,
• geological,
• hard,
• fixed,
• historical,
• artificial,

Simple categories matching hexagonal:

• boundary,