A to Z adverb 3noun 3forms 1 adverb3 •Alphabetical order; lexical order.The listings run A to Z. •From beginning to the end. •Over the entirety; completely. noun3 •All facts related to a subjectThey arrived laden with government reports, books, and assorted papers on the A to Z of welfare […] — 1994 •An encyclopedic or comprehensive guide.an A to Z of cooking terms •(UK) Any of a set of street maps of most British towns and cities; properly the Geographer's A–Z Street Atlas.I always keep a small set of A to Zs in the car. formsA to Zs