Dictionary.com: having no moral standards, restraints, or principles; unaware of or indifferent to questions of right or wrong: a completely amoral person.

Merriam-Webster: lacking moral sensibility <infants are amoral> | being outside or beyond the moral order or a particular code of morals <amoral customs>

Apple dictionary: lacking a moral sense; unconcerned with the rightness or wrongness of something : an amoral attitude to sex.

thefreedictionary.com: Lacking moral sensibility; not caring about right and wrong.

Admittedly, some of these do mention definitions along the lines of "having no moral component", so it looks like everyone was wrong. Hurray!