Do you mean using all the words are just a few?
Incantatem doesn't have a definition, it's part of a spell "Finite Incantatem" which is a general counter-spell. It is a pseudo Latin style word. An "incantation" is the act of using words that have a magical effect when vocalised. The spell above could be pseudo translated as "Stop Incantation" "Fin" meaning stop/end from the Latin "Finem".
Nobody is going to count the number of letters in a Harry Potter books. There are thousands of words never mind letters.
What word does these notes on the staff spell?
Using words with strong connotations
Those letters can be used to spell "crayon".
Words that can be made from the letters in 'acorn' are:aanarccancarconcornnoroaronororcaranroan
The letters GNOITRNE spell the word "nitrogen."
Using some of these letters you can spell the following words:OriginGroinIronyRigorGiroGoryGrinGyroIronRingYogiGinIonNorRigYinYonGoInNoOiOnOrYoYou cannot spell any words using all of the letters.
There are no full anagrams of the letters 'hapomegburner'.Words you can spell using some of the letters are:HamburgerMegaphoneEarphoneHomepageRenumberBurgeonEmbargoEmperorMournerPhonemeProgramRoughenRougherArmourHamperMangerUproarOrphanOrangeGermanBrogueEnough
Here are some of the words which the letters IPRCAIA can spell;CarpParCarArcAriaRapCrapAirPair
No words can be spelled using all of the letters. Some words using some of the letters are:HoldupUpholdProudDropHoldHourLordPlodPourProdDuoDuhHopOldOurPodProRod
Nor ,arc,car,ron,can,ran,
There are no full anagrams of the word "beautiful".Words that you can spell using some of the letters are:FibulaAlbeitFutileBleatBuiltFableFaultFluteTableBailBateBeauBileBiteBlueFailFateFileFlatFleaLateLeafLeftLifeLiftTailTaleTileTubaTube
Usul
fights
The letters 'rdnyoe' can be rearranged to spell the word yonder.Other words that can be spelled using some of the letters (but not all of them) are:DroneNerdyDenyDoneNerdNodeRedoRodeDryEndNodOdeOneOreRedRodYen