IPA: //ˈʌltrəˌsmuːθ//
KK: /ˈʌltrəˌsmuːθ/
Extremely smooth to the touch or appearance, without any roughness or imperfections.
The surface of the new smartphone is ultrasmooth, making it easy to slide your fingers across it.
Comparative: ultrasmoother
Superlative: ultrasmoothest
Ultrasmooth is formed from "ultra-" (meaning beyond or extreme) and "smooth" (from Old English "smoother", meaning free from roughness). The word describes a surface that is extremely smooth, beyond the usual smoothness.
Think of 'beyond' ('ultra-') and 'smooth' to remember that 'ultrasmooth' means extremely smooth.
No commonly confused words.