Modifiers matching oxygen:

• elemental,
• molecular,
• active,
• dissolved,
• atomic,
• abundant,
• bound,
• free,
• pure,

Simple categories matching pure:

• computation,
• worship,
• metal,
• glass,
• material,
• preparation,
• protein,
• fiber,
• disorder,
• compound,
• gas,
• discipline,
• tradition,
• information,
• substance,
• oxide,
• science,
• semiconductor,
• form,
• state,
• source,
• sorbent,
• component,
• oil,
• shape,
• fibre,
• gem,
• product,
• crystal,
• hydrogen,
• manure,
• fluid,
• complaint,
• mineral,
• food,
• matter,
• meat,
• toxemia,
• ingredient,
• silver,
• fruit,
• extract,
• proteinase,
• biology,
• sugar,
• cathode,
• substrate,
• powder,
• fuel,
• translation,
• carotenoid,
• disaccharide,
• nitride,
• activity,
• dielectric,
• entity,
• propellent,
• commodity,
• nutrient,
• oxygen,
• enjoyment,
• clay,
• whimsy,
• art,
• conductor,
• arts,
• alcohol,
• wool,
• narcotic,
• flavoring,
• entertainment,
• color,
• surface,
• carbide,
• fertilizer,
• elements,
• sound,
• feeling,
• fabric,
• fat,
• soul,
• speech,
• essence,
• chemistry,
• alkane,
• pt,
• content,
• cluster,
• enzyme,
• solid,
• liquid,
• water,
• mathematics,
• connection,
• subject,
• phase,
• phenol,
• chemical,
• set,
• notion,
• odour,
• halide,
• alpha-blocker,
• precipitate,
• item,
• placebo,
• contaminant,
• quality,
• thing,
• herb,
• carbohydrate,
• spirits,
• necessity,
• hydrocarbon,
• monosaccharide,
• concept,
• textile,
• system,
• ore,
• emotion,
• antipyretic,
• halogen,
• theory,
• nut,
• study,
• plant,
• smell,
• bread,
• economics,
• abstraction,
• fabrication,
• solvent,
• object,
• analgesic,
• motivation,
• molecule,
• salt,
• starch,
• dish,
• opiate,
• polysaccharide,
• atmosphere,
• carbon,
• mind,
• drink,
• waste,
• idea,
• element,
• drug,
• analysis,
• agonist,
• butter,