At a rate of knots Australia British informal prepositional phrase
Very speedy or rapidly
James drove into the city at a rate of knots when he heard about his brother accident.
Calm down! You're talking at a rate of knots.
We’re progressing at a great rate of knots due to efforts we made after a long period of studying.
Very fast.
Very quick
Very rapidly and eagerly
The phrase came from the mid 17th century when ships' speed was calculated in knots. A knot is one nautical mile per hour. From the mid 19th century, the phrase was extended to mean very fast or quickly.
If someone has a cast iron stomach, they have a strong stomach that can digest unusual food and even bad food without being ill.
Jimmy must have a cast-iron stomach, when he drank milk with lime juice and felt perfectly fine afterward.