古い

1. Origins, structure, and basic meaning

• Structure: 古い is read as ふるい and is an い-adjective for something old in age or worn through use.
• Basic usage: Use it directly before a noun in 古い時計台, and change it to 古く in 鞄が古くなる.

2. Common pitfalls and similar expressions

• Age and wear
  • The clock tower is old historically, while the bag has become worn enough for its handle to need repair.
• Old does not mean unusable
  • 古い describes age or wear and does not by itself say that the tower or bag can no longer be used.