A term used to describe someone who is very direct when conversing on various subjects. Anyone described as having no filter says exactly what is on his/her mind without cleaning up their language, no matter how offensive or politically incorrect it may be.
Boyfriend: Hey, babe. How do I look?
Girlfriend: LOL You look like a Cirque De Solei reject.
Boyfriend: Whoa, you really have no filter. LOL.
This is an adjective to describe a vagina that looks like raw calimari. Or sushi that isn't quite rolled up.
I was going to score with this chick last night when I discovered her filet-o-puss. It looked like it was going to be my last meal and the chef serving me was staring, waiting form me to dig into this salmonella sushi abortion.
When a subject and/or class, usually in higher education scientific fields, is so convoluted and hard to follow, that it is impossible for one to succeed in it. This might be due to the professor, or the subject itself. In this case, the subject acts as a filter, preventing you from moving on to more advanced subjects that built upon it.
This can often extend or apply to specific concepts included or related to a subject or class.
In any of the above cases, it is fair to say that one has been filtered.
-Did you understand anything from the previous lecture?
-No, I'm not even sure the professor understands what he's teaching.
-Huh. I guess we've both been filtered.
Carbon/carbonite filters are used for all sorts of purification. Lately, carbonite filters have been used on bongs. The smoke goes through the carbonite rock, removing carcinogens and other toxins, but not removing the THC. This means you won't cough as much. Regular carbon filters are replaced, while the built in Carbonite brand ones can be cleaned and maintained. It doesn't magically make more THC in your smoke, like the other definition suggests.
Stoner 1: Dude, I love this carbonite filter. It's better than my old ROOR ash catcher!
Stoner 2: Yeah man, just keep it clean.