In 2000 years Waifu has acquired a more specialized meaning in English-speaking culture anime and manga. In the 2002 anime "Azumanga Daioh", some students find a photo that a teacher dropped and ask who the woman in it is. The teacher answers "my wife" in English, which is often transcribed into my "waifu" thanks to Japanese pronunciation and transliteration practices.
The word waifu is a Japanese loan and a translation of the English word "wife"(wife). The origins of this term in Japanese go back at least to the years 1980/1990, when some young japanese have adopted a woman as an alternative to the gender limitations implied by the term traditional kanai, which literally means "inside the house".
Anime fans started using waifu to refer to a character they particularly liked, a character they considered special to them. The first entry in the Urban Dictionary for this use of the word dates back to 2007, and there is evidence that the term, in its anime sense, dates back to at least 2006. It has also spread outside the anime fandom, from so characters from video games or even live TV shows can also be called waifu.
Why and who uses it?
The male equivalent of waifu is the husbando. However, it is likely that this is not from a real Japanese loan word, as the husband's Japanese loan is hazu.
In anime and related otaku, waifu can be used with more or less intensity and is more or less ridiculed or criticized. Some fans may, by chance, call their favorite female character in a game or an anime their waifu. But others are more serious and see their waifu as a part of their life. For these people, their feelings, even if they are well aware that the character is fictional, are serious. Body pillows, resin figures and other merchandise are popular with those who feel their favorite character (the dakimakuras).
A character intentionally created to be lovable, perfect and generally attractive to the viewer can be termed waifu bait on the model of words like jailbai.
Here is ! Now you know everything about what a waifu is!