高額

1. Origins, structure, and basic meaning

• Structure: 高額 is read as こうがく and is a な-adjectival noun for a large monetary amount or high price.
• Basic usage: Add な before money-related nouns in 高額な買い物 and 高額な修理費.

2. Common pitfalls and similar expressions

• Money, not physical height
  • Despite 高, the word concerns how much money is involved rather than the physical height of an item.
• Comparison with expectation
  • 予想以上に says the repair charge was high beyond the level anticipated.