1. Acronym: At The Moment
Describing current activity. For instance: "I am eating ATM, call me later."
2. Acronym: Asynchronous Transfer Mode
Asynchronous Transfer Mode (ATM) is a network protocol that transmits data at a speed of 155 Mbps and higher. ATM works by transmitting all data in small packets of a fixed size named cells; whereas, other protocols transfer variable length packets. ATM supports a variety of media such as video, CD-quality audio, and imaging. ATM employs a star topology, which can work with fiber optic as well as twisted pair cable.
ATM is most often used to interconnect two or more local area networks. It is also frequently used by Internet Service Providers to utilize high-speed access to the Internet for their clients. ATM claim of fame was seamless integration of voice and data, but as telcos convert their voice networks to using IP this is less useful each day. ATM is a dying technology, its telco usage now being replaced by MPLS.
3. Acronym: Automated Teller Machine
Also called a bank machine, this is a 24/7 kiosk interface to one's banking account. Over time, what one may do at such a kiosk has broadened to include printing statements, updating a bankbook, paying bills, transferring money, and more. Some bank machines allow one to withdraw money in more than one type of currency.