1. the technique, method, or system of operating or controlling a process by highly automatic means, as by electronic devices, reducing human intervention to a minimum.

2. a mechanical device, operated electronically, that functions automatically, without continuous input from an operator.

3. act or process of automating.

If we are speaking of the automation of an investment process, such as systematic trading, then we necessarily mean using a computer software to automatically execute decisions without human operation or intervention.