rain (n) - watery precipitation; water that has fallen from clouds, rainwater.
rain (v, intrans) rained, raining - to fall as water from clouds; to fall like rain; to send down rain
rain (v., trans) rained, raining - to pour or administer abundantly
- Hugh never understood that Adele song. How can rain be set on fire? Is it acid rain?
- It rained all day, so the hike was postponed.
- Jag rained blows on his opponent.
- Denise loves the disco song "It's Raining Men."
- The rain in Spain falls mainly on the plain. (Thank you, Henry Higgins.)
- Air pollution is a cause of acid rain.
rein (v, trans.) reined, reining - to control or steer, as with a bit and rein; sometimes used with in.
- Pull the left rein to turn your pony left.
- Jed kept a tight rein on the meeting.
- Stacy was given free rein over the party planning. She could do whatever she liked.
- Chloe, you need to rein in your campers. They're making a huge mess in arts and crafts.
The expression "free rein" specifically means "without guidance" and "full rein" means "without control." They are metaphors based on the practices of letting a horse instinctively find a trail or run at top speed; the rider leaves the reins loose and long (versus tight and short) in either instance, not steering or slowing the horse's free movement.
- To ride east, Eve and Ella rein left.
- Free rein: freedom and speed, whee!
reign (n.) royal authority, ruling power, dominion; the period of rule or dominion.
- Elizabeth II celebrated her Diamond Jubilee in honor of reigning for 60 years.
- King Xerxes reigned from 519 to 465 BC.
- Jessamyn reigns over the entire school like an evil queen.
- Chaos reigns when those kids are left with a sitter.
- Rebels continued their reign of terror for five months.
- Reign of Fire was a film about dragons ruling the earth.
- King George reigns from a glittering, gem-covered throne.
- Gorgeous Gordon reigns the giggling girls at Glenside High.
Increasingly, I've seen people use the expression "free reign," which I'm not entirely certain is a homophone error so much as a new expression with a slightly different meaning than "free rein." It is usually used in contexts of someone exerting total control or behaving like a dictator.
This is an updated post from May 2012.
Do these distinctions help? What other homonyms trip you up?