A term railroad employees use to describe a railroad enthusiast / railfan and the railfan community at large. Most often used disparagingly.
(Engineer to conductor aboard a freight train)

"Man, we got some foamers ahead taking pictures...they need to just get a life and find something to do besides hang around the tracks all day."
by Aeromoe February 28, 2008
The type of n00b who would use derogatory rail slang like SCAXliner or Amtrash, complains about the tuning of train horns, tends to endanger his or other's lives for a good photo, and angers railroad crews through his actions.

Also tends to spam youtube haters' channels, and tend to harrangue people via internet, cell phone, etc.

G: Dude calm down, don't be such a foamer.

*cuts in front of parked train*
by AmtrakFan454 February 11, 2011
A sacrilegious dumbass who simps over trains, more often than not, over a specific railroad or locomotive. A foamer is often ridiculously stupid and is really hard to argue with because they are so naive with the science and art behind railroading and only care about the trains they set eyes on.
Rail Enthusiast: "Damn that foamer foaming hard for some normal NS SD70ACe with the number 1111."
Another Rail Enthusiast: "Don't worry, I see foamers flipping out over an awful looking Caltrain f40ph with a shitty horn, and thats a normal for me."
by UnknownUser225 November 10, 2021
A foamer is a rail fan, most likely someone who has just gotten into the hobby, who foams at the mouth when they see a train.
"The foamer's mouth foamed at the UP Big Boy passing by."
by a idiot lol September 4, 2019
(n). A stereotypical fan who loves to make bias and make fake facts of said hobby. Generally, this term is used by anyone who’s overly obsessed with commonly seen trains. This term is also generally accepted in the bus and aviation community.
Oh my god, that kid really said that bus has a Cummins, but actually has a Detroit Diesel. That kid is a foamer
by 901.lax January 6, 2020
A person who stands by railroad tracks and films or takes pictures of trains
by TwistedXLCyclone July 7, 2021
(1) One who talks alot of non-sense and completely lies about something or someone. (hense having foam in ones mouth and not being able to understand them)

(2) An asshole who says something about someone but doesn't have the courage to back it up.
(1)Dude, He's such a foamer hes choking himself.
(2)He talked shit and didn't even show up for the fight, what a foamer.
by Snwpaint32 June 15, 2007