Aesthetic attraction is a form of tertiary attraction felt by a-spec individuals. It is defined as an attraction to the way someone look, or how they present themselves. It is typically based on a desire to observe someone because one finds them aesthetically pleasing.
For many allosexual/romantics aesthetic attraction is tied to romantic and sexual attraction, but it does not necessarily have to be. It can be described as like looking at a nice painting or landscape; one appreciate the beauty of it, but that does not necessarily mean that one would want to go on a date with it.
An aesthetic crush is known as a swish, although the term is not widely used. One who does not experience aesthetic attraction may identify as a-aesthetic or nonaesthetic.