Taking
literature off the dry, static page and putting it
in your face, incorporating aspects of
storyteller tradition and employing techniques from
drama such as the presentation of
monologues.
Can be poetry, prose or any middle ground - it is how it is presented (pronounced and performed rather than merely recited) which is important.
Jello Biafra calls what he does "spoken word" because it's inclusive and leaves him with many options; poetry, journalism, fiction, stand-up comedy - these are all manifestations of the spoken word, and an effective spoken word practitioner will employ aspects of all of those forms in their work.
Orality.