Modifiers matching impurity:

• dissolved,
• airborne,
• desirable,
• physical,
• nonpolar,
• colloidal,
• undesired,
• ordinary,
• microscopic,
• inorganic,
• random,
• volatile,
• possible,
• light,
• coarse,
• small,
• little,
• foreign,
• minute,
• anionic,
• active,
• hazardous,
• damaging,
• corrosive,
• solid,
• insoluble,
• stubborn,
• dilute,
• common,
• residual,
• fine,
• atmospheric,
• harmful,
• organic,
• soluble,
• gaseous,
• heterogeneous,
• environmental,
• particulate,
• mobile,
• lighter,
• natural,
• smaller,
• minor,
• mental,
• biological,
• polar,
• unwanted,
• heavier,
• absorptive,
• initial,
• suspended,
• sticky,
• harmless,
• off,
• ionic,
• reactive,
• fluid,
• separate,
• homogeneous,
• out,
• mechanical,
• micro,
• unavoidable,
• interfering,
• chemical,
• visible,
• up,
• lightweight,

Simple categories matching colloidal:

• matter,
• gel,
• metal,
• particle,
• earth,
• substance,
• oxide,
• polymer,
• protein,
• material,
• crystal,
• impurity,
• salt,
• structure,
• system,
• fluid,
• medium,
• mineral,
• aggregate,
• nature,
• carrier,
• contaminant,
• state,
• mixture,
• thickener,
• assembly,
• property,
• pattern,
• solution,
• suspension,
• constituent,
• clay,
• paste,
• agent,
• solid,
• sol,
• contamination,
• formulation,
• silver,
• sphere,
• component,
• compound,