Placiosexual is a horny person.
The opposite of placiosexual is iamvanosexual.
Placiosexual is known as a micro-label, meaning that by saying that one is placiosexual it is implied that one is also asexual, or another ace-spec identity. In this case asexual is the primary sexual identity and placiosexual acts as a modifier, making a specific sub-category of asexuals.
Etymology
The prefix placio- comes from the Latin word placere meaning 'to please'.