bluster, brother, buckler, buffer, butler, butler's, butter, cluster, cluttered, color, colour, comer, cover, cupboard, custard, cutler, cutters, drummer, duller, flutter, glover, govern, gunner, gutter, hover, hubbard, hundred, hussars, jugglers, juster, lover, luster, lustre, mother, muller, mustard, muster, mutter, other, plumber, rather, rougher, rubber, rudder, runner, rupture, rutgers, shudder, shutter, smother, smugglers, somers, southern, structure, stubborn, stuttgart, subtler, suburb, succor, succour, sucker, suffer, summer, supper, tougher, tucker, upper, upsurge, upward, usher, utter

another, another's, conductor, discolored, discoloured, discover, instructor, midsummer, recover, uncover

infrastructure, rediscovered, undiscovered