Modifiers matching opening:

• surrounding,
• horizontal,
• natural,
• conventional,
• small,
• typical,
• narrow,
• exterior,
• structural,
• curved,
• necessary,
• outside,
• operational,
• size,
• over,
• outer,
• epidermal,
• circular,
• decorative,
• large,
• larger,
• smaller,
• important,
• gothic,
• fleshy,
• external,
• accessible,
• permanent,
• fine,
• architectural,
• symmetrical,
• prepared,
• mechanical,
• fixed,
• underground,
• off,
• rectangular,
• trim,
• close,
• developing,
• adjacent,
• framed,
• outdoor,
• vertical,

Simple categories matching curved:

• image,
• surface,
• object,
• fruit,
• region,
• end,
• electrode,
• shape,
• body,
• glass,
• reflector,
• structure,
• part,
• form,
• plate,
• scene,
• substrate,
• bone,
• opening,
• outline,
• construction,
• element,
• figure,
• face,
• line,
• bottom,
• pattern,
• entity,
• space,
• piece,
• wall,
• feature,
• portion,
• vessel,
• area,
• article,
• item,
• passage,
• passageway,
• manner,
• section,
• solid,
• side,
• hull,
• elements,
• shock,
• frame,
• boundary,
• work,