Merriam-Webster's Collegiate® Dictionary, 11th Edition
OVERNIGHT
I. adverb
Date: 14th century
1. on the evening before, during the night , very quickly or suddenly ,
II. adjective
Date: 1824
of, lasting, or staying the night, sudden , rapid , traveling during the night ,
4. accomplished by a mail service within one day's time , delivered within one day's time ,
III. verb
Date: 1891
intransitive verb to stay overnight, transitive verb to send (as a package or letter) by a mail service for delivery within one day's time,
IV. noun
Date: 1959
an overnight stay