念入り

1. Origins, structure, and basic meaning

• Structure: 念入り is read as ねんいり and is a な-adjective for being thorough and meticulous enough not to overlook details.
• Basic usage: It modifies an action in 念入りに掃除する and a noun in 念入りな確認.

2. Common pitfalls and similar expressions

• に and な
  • Use 念入りに before a verb and 念入りな before a noun.
• Difference from 丁寧
  • 丁寧 broadly covers politeness or careful treatment; 念入り centers on exhaustive checking or preparation.