Purpose is a word meaning an object to be reached; a target; an aim; a goal; a result that is desired; an intention. Purpose's basic concept is an individual's voluntary behavior activity awareness. Defining purpose is often relatively vague and almost meaningless; however, the concept is valuable and therefore retained.
Purpose can be operational defined as entity class property which may, but need not have consciousness

Consciousness

Consciousness is a term that refers to the relationship between the mind and the world with which it interacts. It has been defined as: subjectivity, awareness, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind...

.
First attested in c.1290, from earl Old French

Old French

Old French was the Romance dialect continuum spoken in territories that span roughly the northern half of modern France and parts of modern Belgium and Switzerland from the 9th century to the 14th century...

 porpos "aim, intention", purpose is related to from porposer "to put forth," from Vulgar Latin

Vulgar Latin

Vulgar Latin is any of the nonstandard forms of Latin from which the Romance languages developed. Because of its nonstandard nature, it had no official orthography. All written works used Classical Latin, with very few exceptions...

 corruption of por- "forth" (Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 pro- "forth") and Old French poser "to put, place".