An alphabetically arranged lexicon of underworld vocabulary that supplies concise definitions and illustrative examples for each entry. The prefatory material frames the compilation as a practical aid for public officers and others who encounter offenders, arguing that familiarizing officials with criminal idioms can assist detection and suppression while acknowledging potential misuse. Entries concentrate on terms used by thieves, grafters, pickpockets, and related figures, covering tools, roles, schemes, and everyday expressions of the criminal milieu. The selection favors essential criminal usages over general slang and encompasses roughly four hundred thirty terms with notes on common contexts and phrasing.