number four
Proposed by a contributor, not yet supported by evidence.
Meaning · English
heroin
Register: slang
Where it’s used:
Used
American English
Sources & notes
Adapted from English Wiktionary (CC BY-SA 4.0, retrieved 2026-07-30 via kaikki.org).
Common questions
What does “number four” mean?
heroin
Is “number four” formal or informal?
number four is generally slang.