ATM
UK[ˌeɪ.tiːˈem]US[ˌeɪ.tiːˈem]
n
A machine, often in a wall outside a bank, from which you can take money out of your bank account using a special card.
n
The abbreviation for 'automated teller machine' or 'automatic teller machine'.
Etymology
The term is a modern initialism originating in the late 20th century. It stands for "Automated Teller Machine" or "Automatic Teller Machine," where 'automated/automatic' refers to the machine's self-operating nature, 'teller' is a term for a bank employee who handles transactions, and 'machine' denotes the mechanical device. The initialism ATM has become the dominant lexical item, effectively replacing the full phrase in common usage and evolving into a standard word in its own right.
Analysis
This is an initialism (ATM) for the compound noun "Automated Teller Machine" or "Automatic Teller Machine". It is not segmented into smaller morphemes based on its current spelling.
Examples
I need to stop by the ATM to withdraw some cash.
The ATM was out of service, so I had to go inside the bank.
He forgot his PIN and couldn't use the ATM.