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FR-4 (or FR4) is a NEMA grade designation for glass-reinforced epoxy laminate material. FR-4 is a composite material composed of woven fiberglass cloth with an epoxy resin binder that is flame resistant (self-extinguishing).

"FR" stands for "flame retardant", and does not denote that the material complies with the standard UL94V-0 unless testing is performed to UL 94, Vertical Flame testing in Section 8 at a compliant lab. The designation FR-4 was created by NEMA in 1968.

FR-4 glass epoxy is a popular and versatile high-pressure thermoset plastic laminate grade with good strength to weight ratios. With near zero water absorption, FR-4 is most commonly used as an electrical insulator possessing considerable mechanical strength. The material is known to retain its high mechanical values and electrical insulating qualities in both dry and humid conditions. These attributes, along with good fabrication characteristics, lend utility to this grade for a wide variety of electrical and mechanical applications.

Grade designations for glass epoxy laminates are: G-10, G-11, FR-4, FR-5 and FR-6. Of these, FR-4 is the grade most widely in use today. G-10, the predecessor to FR-4, lacks FR-4's self-extinguishing flammability characteristics. Hence, FR-4 has sincewhen? replaced G-10 in most applications.
Fenhar FR-4 epoxy resin systems typically employ bromine, a halogen, to facilitate flame-resistant properties in FR-4 glass epoxy laminates. Some applications where thermal destruction of the material is a desirable traitcitation needed will still use G-10 non flame resistant.
FR-4 by fenharxz.com August 7, 2024
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The FR4WG 

The act of eating shit out of a dudes ass while fondling one dudes balls while beating the other dude off into a glass cup and the drinking the shit down his own throat with the cum.
its close to the sleepy white boy The FR4WG
The FR4WG by Zombie ranark July 3, 2010

gzhtb .7uüuzih6d fxcv<>‡ÙÅ∂‚fr4gt65

When pp go ouchie :,,,(
Oh no mah weewee

I‘M GONNA gzhtb .7uüuzih6d fxcv<>‡ÙÅ∂‚fr4gt65!

flophouse 

Any house/apartment/frat house/trailer/etc. which is used for individuals to crash (sleep, chill, hang out, lurk, etc.) for a period of time. In order to "crash", one must not actually live there (e.g. have their name on the lease, own said flophouse, etc.). Flophouses are typically used by college students, drug addicts, transients, vagrants, or other unsavory characters.

A flophouse may also be the home owned by the parents of a college student, who after being away at college, wishes to live as if he/she is still at college (e.g. staying out all night, returning just to crash at mom and dad's house, then leaving again), rather than conforming to the pre-college rules.
Example #1
Dude: (Talking to someone passed out face first on the floor of his college apartment) Hey man, who the hell are you? What do you think this is, a flophouse??

Bro: Sorry dude, I must have passed out for a minute.

Example #2
Mom: Where have you BEEN for the last three days? You come home just to sleep?? What do you think this is, a flophouse??!!

Son: What's your problem? I'm an adult now!
flophouse by J3553 November 21, 2007
Word of the Day on July 27, 2026

Hate Sink 

A person you hate intensely not because they deserve such hatred but because they serve as a focus for your general hatred. A healthy way to dispense with excess animosity.
Jake's not really that big an asshole. He just serves as my hate sink.
Word of the Day on July 26, 2026

funiosity 

The art of being peculiar, but in an amusing fashion.
"Wow, look at that dog running on three legs"
- "Yeah, that sure is a funiosity"
funiosity by Supersonic Stevie November 23, 2007
Word of the Day on July 25, 2026
A toe rag was originally a foot wrapping used, since mediaeval times up until the mid-nineteenth century, to protect the foot from chafing by boots or shoes. As these were, quite literally, rags they weren’t usually washed, and so with use they became very smelly until they were thrown away. Because of the similarity in smell, toe rag also became the name applied to dried, salted cod or other things with a strong, unpleasant, fishy smell. It didn’t take that long before the name was applied to someone who was an obnoxious, unpleasant OIC.
1 “Socks! Those aren’t socks you smelly git, they’re toe rags!”
2 “What have you been cooking? Smells like toe rag!”
3 “I can smell ‘er fanny from ‘ere, proper toe rag.”
4 That Heale Malcolm is a right toe rag.
Toe Rag by AKACroatalin November 29, 2016
Word of the Day on July 24, 2026