These spells are not all the spells in the wizarding world. There are many more, but these are all the spells mentioned in the five Harry Potter books so far.
Accio (AK-see-oh, a-SEE-oh, or a-CHEE-oh) - Summons objects. To summon an object with this spell, the spell-caster must first say "Accio" followed by the object he/she would like to summon. For example, he/she would like to summon a dictionary. Just say, "Accio dictionary!" and the dictionary will fly towards you.
Alohomora (a-LO-ha-MOR-a) - Opens locked objects and doors.
Aparecium (a-par-ES-ee-um or a-par-EE-see-um) - Reveals invisible ink.
Avada Kedavra (a-VA-DA-ka-DAV-ra) - SEE UNFORGIVABLE CURSES
Avis (a-VEES) - Cojures a flock of birds.
Colloportus (co-LO-POR-tus) - Undos Alohomora. Seals doors so it is hard to open again.
Crucio (kroo-SHEE-oh) - SEE UNFORGIVABLE CURSES
Deletrius (de-LECH-ree-is or de-LEE-tree-us) - Disintegrates objects such as the ghost figures of the spells revealed by Priori Incantaem.
Densaugeo (den-SAW-jee-o) -Enlarges the opponent's teeth at a fast rate.
Diffindo (dif-FIN-do) - Cuts/rips objects; thus opening the object the spell is aimed at.
Dissendium (di-SEN-dee-um) - Opens a secret entrance to Hogsmeade through the humped witch statue in Hogwarts.
Engorgio- The enlargement charm, used to make an object increase in size.
Ennervate (EN-er-vayt) - Revives stunned things and people. Opposite of Stupefy.
Evanesco (e-va-NES-ko) - Vanishes the object the spell is aimed at.
Expecto Patronum (ex-PECT-o pa-TRO-num) - Conjures a Patronus which wards away Dementors. This spell requires very advanced magic and is very hard to successfully cast. To cast the spell, you must think of an extremely happy thought and then say the incantation.
Expelliarmus (eks-pel-ee-AR-mus) - Disarms opponent, causing anything he/she is holding to fall out of his/her hands.
Ferula (fe-ROO-la) - Creates bandages that can be used to help a wound.
Finite Incantatem (fi-NEE-tay in-CAN-te-tum) - Ceases the effect of a spell.
Flagrate (FLAG-rayt) - Generates a line of fire which can be altered to create the desired shape.
Furnunculus (fer-NUN-kyoo-lus) - Causes the victim to be covered with grotesque boils.
Impedimenta (im-ped-i-MEN-ta) - Freezes or slows down a target for a short amount of time.
Imperio (im-PER-ee-o) - SEE UNFORGIVABLE CURSES
Impervious (im-PER-vee-is) - Repels water.
Incarcerous (in-KAR-ser-is) - The victim is binded by thick ropes conjured by the spell.
Incendio (in-SEN-di-o) - Emanates flames from the spell-casters wand to create a fire.
Legilimens (le-JI-li-menz) - Allows the caster to read someones mind. This requires very advanced magic.
Locomotor Mortis (lo-ka-MO-tor MOR-tis) - The victim's legs are locked together, making the victim incapable of walking.
Lumos (LOO-mos) - Illuminates the tip of the wand.
Mobiliarbus (MO-bi-lee-AR-bus) - Causes the object to move from its original location.
Mobilicorpus (mo-bi-li-KOR-pus) - Produces invisible strings attached to a person, thus enabling the caster to control the movement of the person. Usually, this spell is used on an unconscious person.
Morsmordre (mors-MOR-druh) - Conjures the Dark Mark - a skull with a serpent pertruding from its mouth. When the Dark Mark is conjured, it means that Voldemort is near.
Nox (NOKS) - Extinguishes the light created by the light of Lumos .
Obliviate (ob-LIV-ee-ayt) - Obliterates the victim's memory. His/her memory can be recovered.
Orchideous (or-KI-dee-us) - Conjures flowers from the tip of the wand.
Pack (PAK) - Not exactly an incantation, itself because of the derivation of the word from the English language. This cleaning spell packs anything needed to be packed.
Peskipiksi Pesternomi (pes-ki-PIK-see pes-ter-NO-mi)- A useless spell, created by Professor Gilderoy Lockhart, supposed to round up pixies.
Petrificus Totalus (pe-TRI-fi-cus to-TAL-us) - This spell binds the victims body, immobilizing him/her.
Point Me (poynt MEE) - Causes the caster's wand to point North, imitating a compass.
Portus (POR-tus) - Makes the object aimed at to become a Portkey-an object used to transport people to another place.
Prior Incantato (pri-OR in-can-TA-to) - Makes the victim's wand produce a vaporous image of the previous spell emitted by the wand. MUST BE AIMED AT THE WAND, NOT TO THE OWNER OF THE WAND.
Protego (pro-TEH-go) - Produces a shield to block the spell aimed at the caster. Helpful to deflect most curses, but not all.
Quietus (kwi-E-tus) - Undos Sonorus. Reduces the sound of the voice of the caster by aiming the spell directly to the throat. If Sonorus has already been casted, the caster's voice will resume its initial volume.
Reducio (re-DOO-see-o) - Shrinks anything the spell hits. If Engorgio has already been casted, the size of the object will resume its normal size.
Reducto (re-DUK-to) - Blasts objects out of the way.
Relashio (re-LASH-ee-o) - Releases the grip of a person/thing.
Reparo (re-PAR-o) - Repairs objects that are broken.
Rictusempra (rik-tu-SEM-pra) - Tickles the victim, causing the victim to laugh uncontrollably.
Scourgify (SKOR-ji-fy) - This spell cleans the object the spell is aimed at.
Serpensortia (ser-pin-SOR-tee-a) - Summons a serpant from your wand.
Silencio (si-LEN-see-o) - Causes the victim to be silent; the victim is unable to talk.
Sonorus (so-NOR-us) - Magnifies your voice by aiming the spell directly to the throat.
Stupefy (STOO-pe-fy) - Stuns its victim.
Tarantallegra (ta-RAN-ta-LEG-ra) - The victim is caused to dance uncontrollably.
Waddiwasi (wa-dee-WA-see) - Pushes things at an incredible speed; helpful for unclogging.
Wingardium Leviosa (win-GAR-dee-um le-vee-O-sa) - Levitates objects.
UNFORGIVABLE CURSESAvada Kedavra (a-VA-DA-ka-DAV-ra) - This spell causes the victim to die. Nothing can revive the victim.
Crucio (KROO-see-o) - Causes the victim severe pain for a short period of time.
Imperio (im-PER-i-o) - Enables the caster to control the victim. Some wizards/witches are capable of fighting it off, however, it is very difficult.