instant message
noun
1.
an electronic message sent in real time via the Internet and therefore immediately available for display on the recipient's screen.
Compare
text message
.
verb (used without object)
2.
to send such an electronic message.
Abbreviation:
IM.
Compare
text
(def 16).
British Dictionary definitions for
instant message
instant message
noun
1.
a message sent using instant-messaging technology
verb
2.
to send an instant message (to)