Modifiers matching nitride:

• refractory,
• stable,
• ceramic,
• exotic,
• metal,
• covalent,
• piezoelectric,
• conductive,
• binary,
• pure,

Simple categories matching covalent:

• element,
• oxide,
• chloride,
• semiconductor,
• material,
• atom,
• solid,
• metal,
• crystal,
• nitride,
• substance,
• system,
• compound,
• structure,
• carbide,