Here are some possibilities:
Similar sounds:
* "Thump" - This is the most common and obvious sound that is similar to "thumb"
* "Thud" - Another similar sound, often used for heavier or more forceful impacts
* "Stub" - This sound is similar in the beginning, but the ending is different
* "Drum" - While not exactly the same, the "d" sound in drum is similar to the "th" sound in thumb.
Words that sound like "thumb" but mean something different:
* "Tum" - This word sounds almost identical but has a different meaning (a low, dull sound)
* "Tume" - This word is less common, but also sounds like "thumb" and refers to swelling
Sounds you might hear when touching a thumb:
* "Click" - You might hear this sound when you bend or crack your thumb
* "Tap" - You might hear this sound if you gently tap your thumb on a surface
* "Rub" - You might hear this sound if you rub your thumb against another surface
Ultimately, the best answer depends on the context. What kind of sound are you looking for?