Rain is water falling from the sky, or a heavy fall of anything: "The rain started before we reached the car." Reign is the period during which a monarch or champion rules: "Her reign lasted forty years." A third homophone, rein, is the strap used to control a horse — and it is the one you need in "free rein" and "rein in".
The core difference
All three words sound identical, so spelling has to be decided by meaning. Rain is weather. Reign is rule. Rein is control.
Rain works as a noun and a verb, and stretches metaphorically to anything falling in quantity: "a rain of criticism", "blows rained down on him".
Reign means to hold royal power, or the period of holding it: "during the reign of Elizabeth I". It extends to dominance in other fields — a reigning champion, a reigning consensus.
The test
Substitute a plain word:
- If rule or rules fits, write reign. "The rule of Henry VIII" works, so it's reign.
- If pour down or downpour fits, write rain.
- If control or restrain fits, write rein. "We must control spending" works, so it's rein in spending.
For spelling, note that reign and sovereign share the same odd eign ending — both belong to monarchy. That pairing is a reliable hook.
The one people get wrong most
The phrase is free rein, not "free reign". It comes from riding: loosening the reins lets a horse choose its own pace. The same image gives rein in, meaning to restrain — "the council reined in the budget", not "reigned in".
Being honest about this: "free reign" is now extremely common, and you will see it in newspapers and published books. The reasoning behind it is not absurd, since a monarch with unchecked power is a plausible image. But dictionaries and style guides still treat free rein as the standard form and free reign as an error, and careful editors correct it. Use free rein.
Examples in use
- "Rain is forecast for the whole weekend."
- "His reign as champion ended in Turin."
- "She gave the designers free rein over the layout."
- "He needs to rein in his temper."
One more pair to watch
Rain check, meaning a postponement — "Can I take a rain check?" — uses rain. It comes from ticketing for weather-affected sporting events. "Reign check" and "rein check" are both errors, though they appear surprisingly often.
Frequently Asked Questions
Is it "free rein" or "free reign"?
Free rein is the standard form. The image is from horse riding: slackening the reins lets the horse go where it likes. "Free reign" is common in print but is still treated as an error by dictionaries and editors.
Is it "rein in" or "reign in" spending?
Rein in. You are pulling something back under control, as you would with a horse's reins. "Reign in" would mean to rule inside somewhere, which is not the meaning.
Is it "take a rain check" or "reign check"?
Rain check. The phrase comes from tickets reissued when a game was rained off, and it now means postponing an invitation to another time.