An address generated by repeated trial until it begins with a chosen string of characters.
Why it matters
A cosmetic preference with a cryptographic cost when the generator seeds badly. Wintermute lost approximately $160m to a documented weakness in the Profanity generator. Addresses produced by standard wallet key derivation are not affected by that class of flaw.
What you can check
A vanity address is a normal address whose key was searched for until the public form matched a chosen pattern. The security question is entirely about the search: how much entropy the generator started from, and whether the tool that produced it is auditable. A short pattern is cheap; a weak generator is cheap to reverse.
Where it showed up
Records in the Incident Tracker that turn on this: Wintermute vanity address key compromise.
Not advice. Definitions are for understanding, not instruction. Nothing here is financial, legal, tax or security advice.