Horanghae (호랑해) is a word used by its glorious creator SEVENTEEN’s performance team leader Hoshi. It’s a combination of two Korean words saranghae (I love you) and horangi (a tiger) so in English it would mean “I tiger you” but people often decide not to translate it. It was created to show love for his fans not leaving out the obsession he also has for tigers. The word is often used with a hand gesture to show his imaginary tiger claws. Horanghae also has inspired Hoshi to add it in the middle of his cover of 10cm. He has also made two originals that includes the word. The word tiger probably means more to him than love so if you hear him say horanghae he means it. Take it as a compliment.

said by Xu Minghao during Seventeen's 5th anniversary special "Shining 5th Anniversary"

Basically it's horang (tiger in korean) and saranghae (I love you in korean) together, but you can't use this if you're not a carat (seventeens fandom name). The word creator is no one else but Hoshi, our favorite tiger😌✨🐯 so everyone, HoRaNgHaEeE~~