Verbs (present participle):
* Singing
* Walking
* Reading
* Dancing
* Learning
* Thinking
* Swimming
* Working
* Playing
* Knowing
Nouns:
* Thing
* Spring
* King
* Ring
* String
* Wing
* Swing
* Sling
* Fling
* Wring
Adjectives:
* Flinging (as in "a flinging motion")
* Wringing (as in "wringing wet")
* Stinging (as in "stinging nettle")
Other:
* Anything
* Nothing
* Something
* Everything
* During
* Among
* Along
Let me know if you want more words or a specific type of word!