However, you could use related words like "sneak" or "stealthy" and add suffixes:
* Sneak:
* Sneaky - adjective (already the base form)
* Sneakily - adverb
* Sneakiness - noun
* Sneak - verb
* Sneaking - present participle
* Snuck - past tense
* Stealthy:
* Stealthily - adverb
* Stealthiness - noun
* Stealth - noun
It's important to remember that the meaning of the word changes depending on the suffix used.