Bisexual - A person whose enduring physical, romantic and/or emotional attraction is to other people of various sexes and/or gender identities. Individuals may experience this attraction in differing ways and degrees over their lifetime.
Just a reminder, just because someone says that they "saw it on the internet" doesn’t make it true.
If you want to know the actual and accurate definition of “bisexual” always consult reputable bisexual academics, organizations and activists. There is a lot of misinformation and shoddy reporting floating around out there. A great deal of it deliberately spread by anti-LGBT and other biphobic/transphobic entities.