快速

1. Origins, structure, and basic meaning

• Structure: 快速(かいそく) denotes fast movement and can also name a type of rapid train.
• Basic usage: It appears both in a train journey and in a description of a ferry's speed.

2. Common pitfalls and similar expressions

• A train category or speed
  • In 快速に乗れば, it refers to the train being boarded. In 快速を誇り, it describes the ferry as boasting high speed.