effere effete efreet efter- errett fekete ferfer ferrer ferret fertee fertek ferter fetter freepr frefre frette fterer fterre k-tree keefer keeffe keeker keeper kepper kereft kerker kertee ketter krefft kreker kretek peeker peepee peeper peerer peeter peetre peffer pepper perere perper perpet perree perret pertek perter pertre peteet petree petrer petter pettet pppppp prefer prefet preffe preket preter pretre prette prkeet r-tree reefer reeffe reeker reeper refeet refeff refert refete refret refter repete repper repref reteer reteet retere retree retret retter t-tree teepee teetee teeter tepper terete terper terrer terret terter tertre tetete tetter treete trefet trefte treker treppe tretee trette