Throughout history, the human image has been used both to illustrate mystical phenomena and to conveniently describe fictional characters. From deities to mythical creatures, their appearances have been described as completely human, as human with a number of altered proportions, or as human with animal body parts. In addition to this, in modern science fiction alien intelligent life is often portrayed as creatures that strongly resemble humans in appearance and body structure. This approach to the imagination of alien life may be due to both the desire to facilitate the perception of non-human characters, and the assumption that life on other planets can develop in approximately the same way as on Earth.

For denoting all of the aforementioned creatures, in recent years it's customary to use the "humanoid" definition. But it's worth noting that despite some similarities between these words, the "humanoid" and "anthropomorphic" definitions are not synonymous. The "anthropomorphic" denotes something that has a number of human characteristics, but has a completely different base appearance and behavior. Meanwhile, the "humanoid" denotes a creature whose body in appearance and structure is as similar to a human as possible.

Recently, the "humanoid" definition mainly denotes a creature similar to a human with such human-like characteristics as bipedalism, an upright torso, hands capable of grasping objects, binocular vision, and feet that are structurally similar to humans. But this definition is inaccurate due to the fact that it uses only the basic features of the human body structure. It can even denote a beastmorphic human which only partially resembles a typical human.

Based on this, it's worth introducing the following extended and more accurate definition.
Humanoid is a single-torso creature that has its own head, torso and arms structurally identical to those of a human, with possible deviations in proportions and specific details. Such details include, but aren't limited to horns, tail, wings, the number of arms and sense organs, the natural covering of the body and locomotion organs.

The following examples demonstrate the deviations of specific humanoids in comparison with a typical human.
Elves, Halflings, Dwarves, Orcs, Goblins, Ogres, Trolls - deviations in proportions.
Angels - addition of wings.
Satyrs - addition of horns and tail, legs replacement.
Cyclops - deviations in proportions, change in the number of sense organs.
Demons, Succubuses - addition of horns, tail and wings, change of the body covering, legs replacement.
Nagas - change in the number of arms, legs replacement.