Angela’s ABCs – Words Easily Confused: Rein and Reign by Angela Caldin
You often see mistakes with these two and that one letter ‘g’ makes a big difference.
Reins are long, thin straps used to control a horse and the word is often used figuratively to indicate that a person is in control of something:
- He held the horse’s reins tightly and felt the animal champ on the metal bit between its teeth.
- When her father retired she successfully took over the reins of the family business.
To give a horse free rein is to hold the reins loosely to allow the animal freedom of movement – it’s the opposite of keeping a tight rein on the horse. These terms are also often used metaphorically:
- The new CEO was given free rein to put a stop to the company’s decline.
- It was vital to keep a tight rein on the food budget.
To rein means to control a horse by pulling on the reins and has an additional figurative sense of to keep someone or something under control – usually seen with ‘in’ and ‘back’:
- She realised that she would have to rein in her spending if she wanted to go on holiday.
- He decided to rein back his drinking which had been getting out of control.
A reign describes the time a queen or king spends on the throne and is used by extension for the period someone is in control or in authority:
- Queen Victoria’s long reign lasted for sixty three years.
- Mrs Thatcher’s reign as prime minister came to an abrupt end when some of her colleagues engineered her resignation.
To reign is used to indicate that a king or queen ruled or held royal office and can also be used to indicate that someone or something is in a position of control or power:
- King Edward VIII, who was never crowned, reigned for only 325 days.
- This spring, the colour pink reigns supreme.
- Steve Jobs reigned for many years at Apple Computers, but not without problems.
verbalberbal 
I’ll never understand why this is so hard for some people, but it must be more difficult than I think because I see these two words confused a lot — by professional writers. At least they’re able to use “rain” correctly. Most of the time.
So good to have your comment – I did think of including ‘rain’ in the piece but then thought that, as you say, most people usually get that right. I’m thinking of writing about ‘horde’ and ‘hoard’ soon because I notice that those two words are often confused.