If you're looking for an English word, it's aesthetics.
If you're looking for a Latin word, it's aesthetica.
Classical Latin had no word for the study of art. The word was coined, in Latin, by philosopher Alexander Gottlieb Baumgarten in 1735 in his master's thesis Meditationes Philosophicae de Nonnullis ad Poema Pertinentibus. The 1765 edition of Baumgarten's treatise Aesthetica begins with this definition:
Aesthetica (theoria liberalium artium, gnoseologia inferior, ars pulcre cogitandi, ars analogi rationis) est scientia cognitionis sensitivae.
Aesthetics (the theory of the liberal arts, the lower theory of knowledge [i.e. pertaining to sense-perception rather than reasoning], the art of comprehending beauty, the art of the sensory world that exists within the faculty of reason [i.e. perception, imagination, comparison, discerning of detail, etc.]) is the science of sensuous cognition.*
Baumgarten was especially concerned to show, contra Plato's dismissal of poetry as a mere imitation of a mere reflection of the true reality, that poetry, by arousing a complexity of sensory images and consequent emotions within the mind, is capable of perfection and worthy in its own right. Hence Baumgarten coined the word from Ancient Greek αἰσθητικός, meaning "pertaining to sense-perception"—the start-point or ground of aesthetic imagination and judgement.
The Dictionary of Untranslatables points out that the word has some ambiguity, because Baumgarten thought that a single independent science should cover sensory perception, art, beauty, and reason's cognition of those things. Some writers have since used the word, in many different languages, more narrowly; some limit it to sense perception and some to beauty.
* Don't take my translation too seriously. I'm not an expert, and Baumgarten may have been using some of the Latin words in specialized 18th-century senses that I'm not familiar with.