Here's some vocabulary related to "swiftly":
Synonyms:
* Rapidly
* Quickly
* Expeditiously
* Hastily
* Immediately
* Promptly
* In a flash
* With alacrity
* At a fast pace
Antonyms:
* Slowly
* Gradually
* Leisurely
* Deliberately
* At a snail's pace
Related words:
* Speed
* Velocity
* Haste
* Urgency
* Hurry
* Rush
Phrases:
* Move swiftly
* Act swiftly
* Swift current
* Swift justice
* Swift decision
Examples:
* The bird flew swiftly through the air.
* She responded swiftly to the emergency.
* The train traveled swiftly across the country.
The specific vocabulary you need will depend on the context in which you're using "swiftly."