Autonomy is the absence of heteronomy. Without autonomy, rational behaviour is not possible. In relation to humans, autonomy means free will and corresponds to a basic principle of digital ethics.
ISO/IEC DIS 22989 autonomous characteristic of a system that is capable of modifying its operating domain or goal without external intervention, control or oversight.
Note 1 to entry: In jurisprudence, autonomy refers to the capacity for self-governance. In this sense, also, ''autonomous'' is a misnomer as applied to automated AI systems, because even the most advanced AI systems are not self-governing. Rather, AI systems operate based on algorithms and otherwise obey the commands of operators. For these reasons, this document does not use the popular term autonomous to describe automation.
ISO/IEC TR 29119-11:2020 ability of a system to work for sustained periods without human intervention
ISTQB - CTAI Syllabus The ability of a system to work for sustained periods without human intervention (ISO/IEC TR 29119-11)