unintentional
About four times more people die as a result of medical error than from all other types of non-deliberate civil wrong.
Experiments such as these help us to appreciate the entirely automatic and non-deliberate nature of natural selection.
She described the process as evolving in a non-deliberate way.

SMART Vocabulary: related words and phrases

Not expected or planned
abrupt end
abrupt halt
abruptly
abruptness
ad hoc
inadvertence
inadvertency
inadvertent
inadvertently
inconceivable
sine die
spirit
spontaneity
spontaneous
spontaneously
unsuspected
untimely
untoward
unwilled
unwitting