Petrarchan adj.

"of, pertaining to, or characteristic of the poetry of Petrarch," 1827 (Keats uses Petrarchal, 1818), from Francesco Petrarch (Italian Petrarca) the poet (1304-1374).

"Petrarchian," not "Petrarchan," as some have it. To begin with, Milton, who is something of an authority, writes "Petrarchian." In the second place, if people want to write English, "Petrarch" is the poet's name, and "Petrarchian" is, according to all analogy, its adjective, In the third, if they want to write Italian, his name is "Petrarca," without any h, and its adjective is "Petrarcan." [George Saintsbury, "History of English Prosody," 1906]