There is no clear definition on it here. Some people say it means to use someone just for sex, and not a person, but then this implies all casual sex. Yet others say it's only if you don't see them as human. so I thought to bring up this comment.

Groping her butt and saying "oi babe u want sum big cock?" that's objectification. Flirting with her but being interested in how she's feeling, her life, interests, hobbies and such is just sexualization.

So this would mean any casual sex or FwB, or really most sex is sexual objectification. This also categorizes any form of sexual aggression (women grope men's butts too) as sexual objectification . And as far as I know most people are not talking about hobbies and interests in the minutes leading up to sex.....

So what is sexual objectification?

note: It's preferable you answer with specific answers and not when you treat her like a human being