upfill pufill ufpill fupill pfuill fpuill upifll puifll uipfll iupfll piufll ipufll ufipll fuipll uifpll iufpll fiupll ifupll pfiull fpiull pifull ipfull fipull ifpull upflil puflil ufplil fuplil pfulil fpulil uplfil pulfil ulpfil lupfil plufil lpufil uflpil fulpil ulfpil lufpil flupil lfupil pfluil fpluil plfuil lpfuil flpuil lfpuil upilfl puilfl uiplfl iuplfl piulfl ipulfl uplifl pulifl ulpifl lupifl pluifl lpuifl uilpfl iulpfl ulipfl luipfl ilupfl liupfl pilufl iplufl pliufl lpiufl ilpufl lipufl ufilpl fuilpl uiflpl iuflpl fiulpl ifulpl uflipl fulipl ulfipl lufipl fluipl lfuipl uilfpl iulfpl ulifpl luifpl ilufpl liufpl filupl iflupl fliupl lfiupl ilfupl lifupl pfilul fpilul piflul ipflul fiplul ifplul pfliul fpliul plfiul lpfiul flpiul lfpiul pilful iplful pliful lpiful ilpful lipful filpul iflpul flipul lfipul ilfpul lifpul upfill pufill ufpill fupill pfuill fpuill upifll puifll uipfll iupfll piufll ipufll ufipll fuipll uifpll iufpll fiupll ifupll pfiull fpiull pifull ipfull fipull ifpull upflil puflil ufplil fuplil pfulil fpulil uplfil pulfil ulpfil lupfil plufil lpufil uflpil fulpil ulfpil lufpil flupil lfupil pfluil fpluil plfuil lpfuil flpuil lfpuil upilfl puilfl uiplfl iuplfl piulfl ipulfl uplifl pulifl ulpifl lupifl pluifl lpuifl uilpfl iulpfl ulipfl luipfl ilupfl liupfl pilufl iplufl pliufl lpiufl ilpufl lipufl ufilpl fuilpl uiflpl iuflpl fiulpl ifulpl uflipl fulipl ulfipl lufipl fluipl lfuipl uilfpl iulfpl ulifpl luifpl ilufpl liufpl filupl iflupl fliupl lfiupl ilfupl lifupl pfilul fpilul piflul ipflul fiplul ifplul pfliul fpliul plfiul lpfiul flpiul lfpiul pilful iplful pliful lpiful ilpful lipful filpul iflpul flipul lfipul ilfpul lifpul upflli puflli ufplli fuplli pfulli fpulli uplfli pulfli ulpfli lupfli plufli lpufli uflpli fulpli ulfpli lufpli flupli lfupli pfluli fpluli plfuli lpfuli flpuli lfpuli upflli puflli ufplli fuplli pfulli fpulli uplfli pulfli ulpfli lupfli plufli lpufli uflpli fulpli ulfpli lufpli flupli lfupli pfluli fpluli plfuli lpfuli flpuli lfpuli upllfi pullfi ulplfi luplfi plulfi lpulfi upllfi pullfi ulplfi luplfi plulfi lpulfi ullpfi lulpfi ullpfi lulpfi llupfi llupfi pllufi lplufi pllufi lplufi llpufi llpufi ufllpi fullpi ulflpi luflpi flulpi lfulpi ufllpi fullpi ulflpi luflpi flulpi lfulpi ullfpi lulfpi ullfpi lulfpi llufpi llufpi fllupi lflupi fllupi lflupi llfupi llfupi pfllui fpllui plflui lpflui flplui lfplui pfllui fpllui plflui lpflui flplui lfplui pllfui lplfui pllfui lplfui llpfui llpfui fllpui lflpui fllpui lflpui llfpui llfpui upillf puillf uipllf iupllf piullf ipullf uplilf pulilf ulpilf lupilf pluilf lpuilf uilplf iulplf uliplf luiplf iluplf liuplf pilulf iplulf pliulf lpiulf ilpulf lipulf upillf puillf uipllf iupllf piullf ipullf uplilf pulilf ulpilf lupilf pluilf lpuilf uilplf iulplf uliplf luiplf iluplf liuplf pilulf iplulf pliulf lpiulf ilpulf lipulf upllif pullif ulplif luplif plulif lpulif upllif pullif ulplif luplif plulif lpulif ullpif lulpif ullpif lulpif llupif llupif plluif lpluif plluif lpluif llpuif llpuif uillpf iullpf ulilpf luilpf ilulpf liulpf uillpf iullpf ulilpf luilpf ilulpf liulpf ullipf lulipf ullipf lulipf lluipf lluipf illupf lilupf illupf lilupf lliupf lliupf pilluf iplluf pliluf lpiluf ilpluf lipluf pilluf iplluf pliluf lpiluf ilpluf lipluf plliuf lpliuf plliuf lpliuf llpiuf llpiuf illpuf lilpuf illpuf lilpuf llipuf llipuf ufillp fuillp uifllp iufllp fiullp ifullp uflilp fulilp ulfilp lufilp fluilp lfuilp uilflp iulflp uliflp luiflp iluflp liuflp filulp iflulp fliulp lfiulp ilfulp lifulp ufillp fuillp uifllp iufllp fiullp ifullp uflilp fulilp ulfilp lufilp fluilp lfuilp uilflp iulflp uliflp luiflp iluflp liuflp filulp iflulp fliulp lfiulp ilfulp lifulp ufllip fullip ulflip luflip flulip lfulip ufllip fullip ulflip luflip flulip lfulip ullfip lulfip ullfip lulfip llufip llufip flluip lfluip flluip lfluip llfuip llfuip uillfp iullfp ulilfp luilfp ilulfp liulfp uillfp iullfp ulilfp luilfp ilulfp liulfp ullifp lulifp ullifp lulifp lluifp lluifp illufp lilufp illufp lilufp lliufp lliufp fillup ifllup flilup lfilup ilflup liflup fillup ifllup flilup lfilup ilflup liflup flliup lfliup flliup lfliup llfiup llfiup illfup lilfup illfup lilfup llifup llifup pfillu fpillu pifllu ipfllu fipllu ifpllu pflilu fplilu plfilu lpfilu flpilu lfpilu pilflu iplflu pliflu lpiflu ilpflu lipflu filplu iflplu fliplu lfiplu ilfplu lifplu pfillu fpillu pifllu ipfllu fipllu ifpllu pflilu fplilu plfilu lpfilu flpilu lfpilu pilflu iplflu pliflu lpiflu ilpflu lipflu filplu iflplu fliplu lfiplu ilfplu lifplu pflliu fplliu plfliu lpfliu flpliu lfpliu pflliu fplliu plfliu lpfliu flpliu lfpliu pllfiu lplfiu pllfiu lplfiu llpfiu llpfiu fllpiu lflpiu fllpiu lflpiu llfpiu llfpiu pillfu ipllfu plilfu lpilfu ilplfu liplfu pillfu ipllfu plilfu lpilfu ilplfu liplfu pllifu lplifu pllifu lplifu llpifu llpifu illpfu lilpfu illpfu lilpfu llipfu llipfu fillpu ifllpu flilpu lfilpu ilflpu liflpu fillpu ifllpu flilpu lfilpu ilflpu liflpu fllipu lflipu fllipu lflipu llfipu llfipu illfpu lilfpu illfpu lilfpu llifpu llifpu
Note: these 'words' (valid or invalid) are all the permutations of the word upfill. These words are obtained by scrambling the letters in upfill.