Modifiers matching boundary:

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

Simple categories matching hexagonal:

• boundary,