What does "덕심" mean?

Question

Answer

덕은 오타쿠를 뜻하는 말이고 심은 마음을 뜻하는 말인데,
오타쿠가 애니에 빠져있는 마음으로 해석해도 되고,
애니나 게임과 상관 없는 상황에서는
팬심과 비슷한 의미로 해석하면 되는 단어이다.

덕 means "오타쿠(Otaku)"
심 means "mind, heart"

덕심 means "the mind of an otaku"
덕심 can be used as 팬심
팬심 means "Someone who is a hardcore fan of something but is discrete about it."

Answer

덕심 is an Internet slang 덕 + 심.
덕 came from Japanese slang "Otaku"(Geek in English). 오타쿠 was changed into 덕후 or 덕.

심 is Chinese character 心(heart or mind in English) translated as 마음. For example 이해심.

덕심,덕후의 마음 mind of geek, is currently treated as the same meaning with  팬심 heart of fan.