worst + -est <span class="searchmatch">worstest</span> (nonstandard) Worst. 1847, Thomas Preskett Prest, Varney the vampire; or, The feast of blood.[1]: Of all the blessed insults rolled...
Worst may be further inflected to form the two additional superlatives <span class="searchmatch">worstest</span> (nonstandard) and worstestest (informal, humorous). The comparative worser...