not deliberate; accidental: the killing had been unintentional.

What do you mean by unintended?

: not planned as a purpose or goal : not deliberate or intended an unintended consequence/effect an unintended pregnancy.

What is the synonym of accidental?

1'accidental damage' fortuitous, chance, occurring by accident, occurring by chance, adventitious, fluky, coincidental, casual, serendipitous, random, aleatory. unexpected, unforeseen, unanticipated, unlooked-for. unintentional, unintended, inadvertent, involuntary, unplanned, unpremeditated, unthinking, unmeant.