What's the past participle of "swim"?

Eat, ate, eaten. Throw, threw, thrown. Swim, swam, and... what?

Every time I teach this word, I swear half the class doesn't believe me.

The answer is swum. And when I tell them, they look at me like I made it up. One student suggested the past participle was swammen.

But yes — it's swum:

• I swim every day.

• I swam every day last week.

• I have swum every day this week so far.

These are correct. Get used to them.

And swum isn't the only one. There are many others.

Borne, as in food-borne illness, is the past participle of the verb to bear, as in to bear a weight or I couldn't bear to disappoint him.

This works with negatives, too. The word ruth means compassion — but you already knew that because you already know ruthless.

Less-common forms of words you already know—they're like coins in the sofa cushions. They're already there. You just have to dig them out.