Definition: Delivery Traffic Indication Message. A DTIM is a signal sent as part of a beacon by an access point to a client device in sleep mode, alerting it that a packet of data awaits delivery.

Related Links

Delivery traffic indication message – Wikipedia
DTIM – Delivery Traffic Indication Message – Mpirical
What is the wireless DTIM? And how do we use it? – Airheads Community
Default beacon/dtim settings – Cisco Support Community