Modifiers matching ground:

• convenient,
• soft,
• woven,
• working,
• neutral,
• mechanical,
• barren,
• rough,
• off,
• uneven,
• high,
• metal,
• hard,
• sacred,
• disturbed,
• waterlogged,
• flat,
• white,
• open,
• private,
• up,
• paved,
• stable,
• routine,
• low,
• slippery,
• clear,
• new,
• level,
• moist,
• metallic,
• safe,
• durable,
• grown,
• irregular,
• particular,
• softer,
• sized,
• sensitive,
• wet,
• loose,
• higher,
• unstable,
• common,
• harder,
• over,
• dangerous,
• uncultivated,
• bad,
• sandy,
• shiny,
• vertical,
• weak,
• technical,
• familiar,
• permeable,
• rigid,
• difficult,
• elevated,
• natural,
• rocky,
• under,
• dry,
• old,
• clean,
• undisturbed,
• artificial,
• unsecured,
• heavy,
• coarse,
• holy,
• good,
• porous,
• firm,
• electrical,
• conductive,
• hazardous,

Simple categories matching difficult:

• location,
• substrate,
• tumour,
• problem,
• area,
• illness,
• emotion,
• surface,
• artifact,
• infection,
• vessel,
• pose,
• period,
• material,
• labor,
• concept,
• structure,
• behavior,
• stain,
• condition,
• matrix,
• polymer,
• feeling,
• process,
• rock,
• item,
• shot,
• language,
• conflict,
• disease,
• subject,
• institution,
• job,
• course,
• system,
• picture,
• group,
• event,
• compound,
• peak,
• substance,
• times,
• target,
• profession,
• science,
• tank,
• circumstances,
• zone,
• soil,
• work,
• image,
• years,
• instrument,
• place,
• quarry,
• flow,
• contaminant,
• math,
• text,
• particle,
• fibre,
• space,
• tray,
• treatment,
• component,
• product,
• suit,
• odor,
• weather,
• pregnancy,
• information,
• article,
• fuel,
• fiber,
• crossing,
• time,
• food,
• terrain,
• reality,
• dermatosis,
• card,
• behaviour,
• stone,
• surgery,
• insecticide,
• measurement,
• trait,
• environment,
• discipline,
• disorder,
• content,
• hardware,
• installation,
• placement,
• site,
• powder,
• activity,
• stuff,
• plastic,
• issue,
• delivery,
• ground,
• matter,
• bond,
• deposit,
• obstacle,
• situation,
• articulator,
• class,
• question,
• metal,
• sector,
• medium,
• coating,
• maneuver,
• sugar,
• region,
• fabric,
• fluid,
• fire,
• works,
• commodity,
• symptom,
• texture,
• original,
• joint,
• video,
• shape,
• position,
• setting,
• carbohydrate,
• container,
• part,
• mission,
• idea,
• object,
• topic,
• point,
• feature,
• injury,
• case,
• concern,
• cave,
• dirt,
• waste,
• state,
• apparatus,
• dog,
• signal,
• access,
• thing,