一刻

1. Origins, structure, and basic meaning

• Structure: 一刻 (いっこく) combines one 一 and time unit 刻 to denote a brief moment.
• Basic usage: It appears in urgent expressions about treating an injury or contacting family as soon as possible.

2. Common pitfalls and similar expressions

• Urgency rather than a precise duration
  • In 一刻を争う and 一刻も早く, the word intensifies “without delay” rather than measuring an exact number of minutes.