lurker

1. (Internet slang) A user who observes a community rather than participating; someone who reads or takes advantage of content on a website, newsgroup, etc. but does not contribute.Examples: "However, less than half of lurkers went online that often. Those who post also are more likely than lurkers to use the Internet for both work and pleasure. Posters use the Internet to communicate more with others than lurkers do."; "It’s not unusual for people to join video calls with their camera off and microphone muted, but such lurkers can at least be called upon to speak."Antonyms: posterInternet

2. (archaic, UK, dialect) A small fishing-boat.UKarchaicdialectal

3. (obsolete slang, UK) An impostor; a quack.Examples: "In every large town sham official documents, with crests, seals, and signatures, can be got for half-a-crown. Armed with these, the patterer becomes a ‘lurker,’—that is, an impostor; his papers certify any and every ‘ill that flesh is heir to.’"UKobsoleteslang