It's usually in the form of a Reverse Harem, but it can also be used in regular harems.
But instead of all the love interests loving the protagonist, everyone hates the protagonist!
A genre in manga and anime where a single (often ordinary) girl is liked and followed by a bunch of handsome men (3 or more) who are all madly in love with her. The girl often cannot pick which guy she should go out with and remains indecisive.
The male version of this is harem
Ouran high school host club and the wallflower are reverse harem manga/anime.
A genre in anime and manga that every weeb indeed watches, however it is never discussed among fellow weebs.
A harem is essentially when there is a boy who is bombarded by a bevy girls presenting various physiques. The girls in the harem are all attracted to the boy and often fight over his affection. A Harem can be metaphorically describes as a rooster in a henhouse.
Max: Yo, have you seen that new harem that just got added to crunchyroll?
A man who is surrounded by girls but can never choose which one to marry or which one to be his girlfriend. Typically is a male who goes to a Japanese school and either is awesomely smart, extremely kind, or just a badass.
Player 1: Hey dude, is it just me or does {Kirito} have a lot of babes with him?
Player 2: Yes he does, he has now been crowned the Harem King of {Sword Art Online}
Player 1: Aw man, how do I become a Harem King now?
Player 2: You either do everything you can to attract girls or become a {Kirito}.