An antiprism is a part of geometry, and its shape is very unique.

The shape of this object is very unique.

It's difficult to calculate the volume of this prism.

He participated in the anti-war movement.

He is participating in the anti-war movement.

He made a model of a triangular prism.

He made a lamp in the shape of a hexagonal prism.

An antiquark is the antiparticle of a quark.

An antiparticle is a particle that pairs with a matter particle.

He invented an anti-gravity device.