Ecchi (or Etchi, from the Japanese エッチ etchi) is derived from a Japanese word meaning "lewd", "sexy", "lascivious", or "naughty" when used as an adjective, or sexual intercourse when used as a noun.
Japanese usage
Ecchi is an English word deriving from a Japanese word meaning "lewd" or "naughty" when used as an adjective, it may alternatively refer to a pervert or sexual intercourse when used as a noun.
The word sekkusu is also used in Japan for sex, and Japanese native words for sex (such as 性交 seikō) are often replaced by words of foreign origin such as sekkusu or neologisms such as ecchi. The nuance of ecchi varies with context, but in general the word itself is comparable to the English words "naughty" or "dirty" (when used as an adjective). The prefix "H-" is sometimes used to refer to pornographic genres: H-anime, H-manga, etc.
*from Wiki
