Aerate and air raid are easily confused terms. While aerate is a verb and just one word, air raid is a verb phrase.
The spell-check application of most word processing software programs would not catch a slip-up of these two words. Spell-check is looking for words that aren’t in its dictionary, and words that resemble words in its dictionary but are possibly spelled wrong. Spell-check isn’t perfect. It doesn’t know and can’t guess what word you wanted or what word you meant, it can only judge the words on the page. If you used words that are all spelled correctly, it gives you a pass anyway.
Autocorrect suggests words that start with the same letters. It’s suggesting what word you may want to save time, but quite often, its suggestions are pretty off base. They don’t help you out, but they do make you laugh.
Aerate (“err-rayt”, “eh-uh-rayt”) is a verb. It means to expose a substance to air in order that the air permeates the substance. When a bottle of wine is opened, it is aerated before pouring. Gardeners and farmers aerate their soil with holes in order to allow water and nutrients to seep in.
Air raid (pronounced “err ray-d”) is a verb phrase. It means a bombing or other attack made by aircraft flying overhead. While air raids were conducted by human pilots in 20th century battles, today, 21st century battles often involve drones, a type of UAV (unmanned aerial vehicle).
The following story uses both words correctly:
Aileas was aerating the soil on her family farm when the alarms began to sound. An air raid was happening at any moment and he had to get to the shelter as soon as possible. It wasn’t easy with his limp, but she made it.