The phrase "outdated notion" refers to an idea or belief that is old-fashioned, no longer relevant, or no longer widely accepted in society. Full definition
You should therefore rid yourself of outdated notions of being the «master» of the relationship, and instead work to establish a foundation of trust and mutual respect. (sugardaddylot.com)
Justice Corrigan's objections are based on outdated notions of judicial impartiality. (news.lawreader.com)
I'm a little concerned that speculating further than that would rely on some pretty outdated notions about women gamers, such as the stereotypes that they are only interested in casual games or that they only like games with cutesy graphics. (dromble.com)