What characteristic defines acrylic paint?

The defining characteristic of acrylic paint is that it is water-soluble and fast-drying. This means that, when wet, acrylic paint can be easily thinned and cleaned up with water, making it a user-friendly option for many artists. Additionally, this fast-drying property allows for quicker layering and rapid completion of artwork compared to oil-based paints, which typically take much longer to dry. The ability to use a variety of mediums with acrylics, including water or other additives, while maintaining their water-soluble nature, further emphasizes the versatility and unique qualities of acrylic paint.