IPA: //ˌʌltrəˈpaʊərfəl//
KK: /ˈʌltrəˌpaʊərfəl/
Extremely powerful or having a very high level of power and influence.
The new engine is ultrapowerful, allowing the car to reach high speeds quickly.
Ultrapowerful → It is formed from "ultra-" (meaning beyond or extreme) and "powerful" (from Old French *pouor*, meaning having power). The word "ultrapowerful" means having power that is beyond or extremely powerful.
Think of 'ultra-' meaning beyond, and 'powerful' meaning having power — so ultrapowerful describes something that has power beyond the usual.
No commonly confused words.