inadvertent – not resulting from deliberate planning; unintentional
(Pronounced in-ad-ver-tnt)
To remember the definition of the word inadvertent, use the following mnemonic:
In the advert, it said the ants (inadvertent) were harmless, but they unintentionally sent me venomous ones.

Examples of inadvertent in a sentence
Inadvertent contamination of some food products has been uncovered.
An inadvertent administrative error occurred that resulted in everyone getting paid 1p.
Studies show that persons deemed beautiful by social norm receive inadvertent preferential treatment.