Definition of shortens:
(v) :
(transitive) To make shorter; to abbreviate.
(v) :
(intransitive) To become shorter.
(v) :
(transitive) To reduce or diminish in amount, quantity, or extent; to lessen.
(v) :
(transitive) To make deficient (as to); to deprive (of).
(v) :
(transitive) To make short or friable, as pastry, with butter, lard, etc.
(v) :
(baking, of pastries, transitive) To make crumbly.