According to the Merriam-Webster online dictionary, the word "vocal" dates to at least the 14th century and comes from the Latin word "vocalis," which means "uttered by the voice" or "relating to, composed or arranged for, or sung by the human voice." "Media" is the plural of "medium" and refers to the means of communication--in this case, singing.
The song, the German "lied," the ballad, the aria, and the psalm are all media through which humans have expressed themselves through the ages. Different cultures developed their own unique forms of singing with particular scales and rhythmic styles, such as the Bhajans, which are a very popular form of Hindu devotional song.
Each country has its national anthem, and folk songs are an important reflection of a nation's culture. The composer Vaughan-Williams notated the songs of local countrymen that influenced his symphonic music, and song is a vocal media form that has been developed into a high art by such composers as Franz Schubert.