Given how Vajarois became a wailing ghost upon death, ghosts are proposed to be the restless spirit of the dead bound to the mortal world due to certain circumstances surrounding their death. They mostly appear as human-sized, spectral entities with barely humanoid appearance, possessing long arms, stubby legs, and a head with few to none visible features (though one is shown to has hair-like appendage). In case of Vajarois however, she has visible mouth and eyes as well as around the size of a Titan — this is not natural, however, as her current ghost form was the result of her consuming a Seed of Sorrow out of grief from losing her friends in life: The Seed anchored her soul to mortal world and kept her in a constant sorrow until Akko, Lotte, and Sucy removed it, freeing her and allowed her to pass on.
Only those who can perform magic such as Wild Hunters, Witches, and possibly Wizards who able to perceive the ghosts. The ghosts also susceptible to magic, as magic weapons utilized by Wild Hunters and magical weaponry of Stanship can easily neutralize them, banishing them back to the realm of the dead they belonged at.
Due to their non-corporeal nature and can only be perceived by those who have a degree of magical skills like witches of wizards, the ghosts can be confused with Spirits. In spite of their similarities, it should be noted that spirits and ghosts are actually separate types of entities: Whereas spirits are non-corporeal magical beings manifested from objects that went past a hundred years, ghosts are the disembodied soul of once-living creatures, and thus technically are undead beings.
Powers and Abilities
Being non-corporeal entities, ghosts can pass unnoticed by non-magical humans. Other than levitation, flight, and teleport (as ghosts are observed to appear seemingly out of nowhere during Wild Hunts), their abilities are yet to be fully explored. Through Vajarois, anything that ghosts devour would be expelled with little to no harm.
Croix's pixels can endow ghosts corporeal form, enabling them to be perceived by non-magical humans as well as exploiting the device's ability to combine into monsters as shown in "Sky War Stanship". Similarly, the Seed of Sorrow can endow a ghost a semi-corporeal state to perform the same feat.Similar to their popular depictions, ghosts can emanate ectoplasm from their very being. In fact, their spectral form is comprised of this very substance, though its concentration seemed to depend on ghost themselves: Weaker ghosts' ectoplasm would instantly evaporate into nothingness upon being banished to the land of the dead, whereas stronger ones, such as Vajarois', dissolve into goo-like form before evaporating completely.