My personal definition of a therian, therianthrope, were, Animal-kin, or your preference of term:
A therian is someone with a deep, open personal connection to an animal spirit or animal spirits. Sometimes these connections come mentally, physically, or spiritually; whatever the case, therians are people who are deeply connected to a side of themselves that is animal in nature. It's like having a part of yourself that is totally non-human, and yet is so intricately linked to you that you aren't you without it. Some people have more than one animal-side, which is why I said spirits. Not all therians are wolves.
Think of therianthropy as something like spiritual dysphoria - our inside spirit and our outside body don't match.
Some people feel that therians of all kinds are not truely Otherkin, as they aren't a human host with a reincarnated Kin inside, and yet others believe that they are as Otherkin as any elf, sylph or dragon. I'm one of those people.
Yeah, yeah - so that might not be the most concrete definition. I have a hard time with defining therianthropy specific to me, let alone in general. However, Trikster L once wrote a very good (IMO) bit on the concept of what a therian is, and I will share it with you.
A were is a human being who has a deep, spiritual connection to a specific animal, or, in some cases, two or more animals. This goes deeper than simple admiration, definitely deeper than "hey, that's kinda nifty, I'm like that." It goes in a slightly different direction than totemism; you can call it deeper if you want.
To an extent, weres believe they are the animal; to what extent varies with the individual. Quite often weres will act like their animal, but it would be a mistake to call this "acting"... it ends up feeling closer to just "being yourself" than anything else. Weres have (usually inherent) personality traits that reflect their animal.
Weres usually have a strong sense of belonging in wild places; outdoors is home, and being outdoors is very satisfying. By the same token, being in places that are crowded, or overbuilt, or that have had their natural ecosystem destroyed, usually make weres feel out of place, at the least.
To contrast: Furries do not usually claim to have a spiritual affinity for their animal. Totemists do not usually claim to be their animal. Humans do not normally see anything wrong with co-mingling in large groups or working, sleeping, and living their entire lives in a megalapolis such as Chicago or Los Angeles without ever leaving it.
An animal-side is an internal spirit. You ARE your animal-side - it is your spirit. For the most part, it should not be (at least in my opinion or experience) a separate spirit within you. These "sides" can often get confused with a few other concepts of animal spirits, totems and spirit guides. Both totems and spirit guides are external spirits - they don't reside within you all the time.
A totem is an archetypal spirit, the essence of a species of animal. For example, they are not just one individual wolf - they are Wolf, all that it means to be and has ever meant to be as a wolf. Totems come and go through peoples lives, bringing teachings and lessons to bear when their medicine is needed. Some totems are more personally linked than others - one may appear through a summer to teach a lesson, and one may walk with a person their entire lives to help guide them and support them when they are needed.
Totems will sometimes "walk-in" to people - as in you will shift into the totem's form, or they will take you over to help yoiu understand something you could not otherwise. This can be confusing to the animal-person they are teaching - it can feel very similar to a normal shift, and those with many totems or changing totems often wonder if they are developing a second (or more) wereside in addition to their original known ones.
A spirit guide is an individual spirit of an animal, creature, plant, rock, person, etc. It isn't an archetype - just a spirit that has decided to be your companion for as long as it wants to be, and will help you however it can with its' own knowledges and experiences. It's a spiritual friend and companion that will help you as much as it can - but they're not as omnipresent as a totem, and they're not your wereside.
There is a "were community" online these days - it started off small, back in the days of AHWW in the mid '90s. Since then, other message boards and websites have risen and fallen, in the cyclical nature of things Internet. Today we have larger numbers than ever before, swelled by the numerous young people who have "grown up" online and are finding themselves identifying with therianthropy at younger and younger ages.
Next Section:
Theriotype, or Finding the Animal Within