大きい

1. Origins, structure, and basic meaning

• Structure: In 大きい (おおきい), large stem 大き plus adjectival い forms the adjective big.
• Basic usage: 大きい applies to physical size and to the degree of a difference, effect, sound, or similar quality.

2. Common pitfalls and similar expressions

• Physical size and abstract degree
  • 大きかった places that quality in the past, so both the target and tense matter.