Definition of postcodes:
(n) :
(UK, Ireland) A sequence of letters and numbers added to a postal address to aid the sorting and delivery of post or mail.
(n) :
(Australia, New Zealand) A four-digit number added to a postal address to sort and deliver mail.
(n) :
(by extension) The region denoted by such a sequence.
(v) :
(UK) To give a postcode to; to mark with a postcode.