alee,ashen,ashy,band,bare,bark,barm,bate,boar,boat,bowl,brag,bran,brand,brawl,bray,cant,cape,caper,care,cart,code,cone,cope,coper,cowl,dado,dawn,done,eaten,fare,farm,farm,fate,feel,fend,fire,fore,frown,gage,gape,gash,gasp,gate,hash,hasp,hate,here,hope,howl,kink,lawn,lope,mage,manage,many,mare,mark,mart,mate,mope,mown,nape,node,open,opera,operate,pale,pall,pant,paper,pare,park,part,pawn,pear,peat,peat,pink,pope,prod,prow,prowl,rage,rant,rape,rapt,rate,reft,rode,sage,sago,sate,sawn,sear,seat,shew,sink,skid,skin,skit,sold,sown,spall,span,spar,spare,spark,spat,spate,spawn,tape,taper,tare,tart,tear,teat,tend,them,then,there,tone,tore,town,wage,wand,want,ware,warm,wart,wash,washy,wasp,wend,whop,wink,year,your
A list of some words that follow that rule...
Some of the longest :
OPERATE -> OPE -> to open (poet.); PER -> meter PER second;
ERA ->...;RAT->...;ATE->...;
MANAGE -> MAN->...;ANA -> anecdote or literary gossip about a preson;NAG -> to irritate...;AGE -> ...
I used a dictionary of aprox. 60000 words...not 500000...but I think it's good enough...it has words from many domains (economy,mechanics...)