Chapter 1 of Introduction to Psalms by Hermann Gunkel contains the following quote:
The primary preliminary task will be to provide an overview of the entire material transmitted to us. The reason is self-evident. It cannot be satisfactory simply to observe the poetry of the biblical psalter. Rather, one must ask whether there are psalms or psalm-like poetry outside the psalter... [W]e cannot remain just in the cabinets of Israelite convention. We must also peruse the lyric of other nations of antiquity to see whether we perceive something similar. For decades we have recognized the extraordinarily rich cultic poetry of the Babylonians and Assyrians, from which many specimens have demonstrated a relationship to the biblical psalms that is more than superficial. It has long been recognized, but has not been satisfactorily taken to heart in Psalms research.
Is the author saying here that Psalms are cultic poetry (and that, conversely, all cultic poems are also Psalms)? What is his definition of a Psalm here?