Apossar means "to take possession of" or "to seize." It's a strong verb that goes beyond simply having something, implying a more active and determined act of claiming.
In the context of the song, the singer expresses a deep desire to "me apossar dos seus abraços" (take possession of your hugs) and a piece of the beloved's heart. This word highlights the intensity of his longing and his yearning to fully claim the affection of the person he loves.
"Te Possuir" is Gusttavo Lima leaning hard into wanting, not the soft kind of loving. He opens gentle enough, "Queria ouvir tua voz, sentir o gosto do seu beijo" [I wanted to hear your voice, taste your kiss], asking for just a piece of her attention, "pelo menos um pedaço do seu coração" [at least a piece of your heart]. Then the chorus drops the patience entirely: "Vou te pegar, te agarrar, te consumir" [I'''m going to get you, grab you, consume you]. That'''s the whole song, one guy going from polite longing to flat-out declaring he'''s going to take what he wants.
The line "Quero te amar, te possuir" [I want to love you, possess you] repeats so often it stops sounding romantic and starts sounding almost obsessive, which fits this Ao Vivo em São Paulo recording, cut live with a full crowd shouting every "eu vou me jogar em você" [I'''m going to throw myself at you] back at him. It plays less like a love song and more like a countdown to a decision he'''s already made.