A baseline is a series of notes that often go with and support a melody line. A prominent example of this is in today's modern rock music, in which a bass guitar will play repeating notes that harmonize with the lead guitar's melody line.
Printed copy · Anthology Volume 2, page 30Printed copy from The Tender For Law Anthology, Volume 2, page 30 (printed 14 June 2014). Added by this site; not part of the Facebook export.