What does HTTP status 404 mean, and how can you peg it as a single word?

404 → "racer" (r·s·r).

404 Not Found means the server reached your request but has no resource at that URL — the Web's most famous error. The digits 4·0·4 are the sounds /r/·/s/·/r/, which spell racer: picture a racer skidding off the edge of a missing page.