Stra-tum, haen; gwanaf; gwely
Stream-ing, ffrydiad; ffrydiol
Stream-let, corffrwd, ffrydan
Strength-en, nerthu, grymuso
Stretch-er, ymestynwr; tynfaingc
Strict-ness, caethder, manylrwydd
Strik-ing, hynod, nodedig; od
Strin-gent, bolrwymol, caethrwym
Strip-ling, glaslangc, llencyn
Struc-ture, adail, adeiladaeth; ffurf