Incorrect spelling, explanation: the right form of this word – swimming – is a derivative of the verb swim. That means swim is its root. When creating a present participle/gerund, we must remember to double the last (and stressed as well) consonant (-m), because there’s a single vowel before it. That is the reason why the right form is swimming, not swiming.

Correct spelling, explanation: the word swimming is a present participle/gerund of the infinitive to swim. It originates from an Old English swimman. This derivative must be spelled with the double -m, because of an important rule: when there is a single vowel before the last (and stressed as well) consonant in a word, we need to double that consonant. That’s why you can’t use the form swimming.

Definition of swimming:
1. noun (gerund), an act of moving through water by moving the whole body or its parts
Swimming has been my hobby since I was little.
My father showed me that swimming isn’t hard.
2. verb (the present participle), propelling the body through water by using the limbs
I can’t talk to you right now, I’m swimming in the pool!
Mary is swimming and enjoying herself.

Collocations with swimming:
Some most commonly used collocations include: swimming in the deep, swimming in the ocean, and swimming freestyle.