What is the meaning of Otaku?

One with an obsessive interest in something, particularly an obsessive Japanese fan of anime or manga.

otaku

otaku (one with an obsessive interest in something such as anime or manga)

Rōmaji transcription of おたく

Rōmaji transcription of オタク

otaku (person with an obsessive interest in something, particularly obsessive Japanese fans of anime or manga)

weeb (one with an interest in something such as anime or manga)

otaku, weeb (a person with an interest in things such as anime or manga)

Source: Wiktionary