Modifiers matching headache:

• major,
• secondary,
• primary,
• common,
• simple,
• severe,
• vascular,
• underlying,
• persistent,
• serious,
• intense,
• debilitating,
• episodic,
• throbbing,
• paroxysmal,
• chronic,
• recurrent,
• psychosomatic,

Simple categories matching underlying:

• allergy,
• documentation,
• act,
• disease,
• condition,
• mechanism,
• lesion,
• illness,
• part,
• pathology,
• content,
• disposition,
• signal,
• disorder,
• investment,
• assets,
• seizure,
• theory,
• material,
• commodity,
• component,
• fear,
• structure,
• fact,
• cause,
• property,
• interaction,
• process,
• relationship,
• device,
• arrangement,
• catastrophe,
• instrument,
• concept,
• section,
• asset,
• transaction,
• deformity,
• incident,
• work,
• server,
• anemia,
• right,
• biotechnology,
• reason,
• technology,
• disturbance,
• index,
• activity,
• trait,
• surface,
• determinant,
• skill,
• tax,
• ailment,
• substrate,
• course,
• resource,
• malignancy,
• felony,
• cancer,
• values,
• shape,
• force,
• input,
• characteristic,
• meaning,
• construction,
• factor,
• collateral,
• event,
• issue,
• psychosis,
• market,
• holding,
• agreement,
• difficulty,
• tumor,
• protocol,
• notion,
• difference,
• tissue,
• rock,
• value,
• receptacle,
• base,
• end,
• fibrosis,
• cognition,
• metal,
• diathesis,
• partnership,
• state,
• impairment,
• complication,
• variable,
• emotion,
• sediment,
• hardware,
• product,
• deposit,
• distribution,
• quality,
• headache,
• ownership,
• problem,
• discipline,
• document,
• works,
• agent,
• idea,
• hypersensitivity,
• data,
• fraud,
• development,
• ability,
• offense,
• abnormality,
• table,
• ratio,
• file,
• mineral,
• hazard,
• medium,
• feature,
• software,
• organs,
• attribute,
• behavior,
• item,
• payoff,
• interest,
• share,
• compartment,
• dermatosis,
• attitude,
• entity,
• film,
• area,
• layer,
• connection,
• skin,
• manifestation,
• terms,
• intervention,
• symptom,
• support,
• substance,
• phenomenon,
• action,
• arthritis,
• task,
• liabilities,
• theme,
• measure,
• transport,
• inflammation,
• addiction,
• object,
• principle,
• infection,
• system,
• insurance,
• situation,
• motive,
• security,
• contract,
• misconduct,
• network,
• crime,
• image,