The word 'busha' appeared in the famous phrase, '松影是雖武者子孫' (Matsukage was the true descendant of busha), in "Oraimono" (a textbook for common people) during the mid-Heian period.
「武者」という言葉なら平安時代中期の『往来物』の、有名な「松影是雖武者子孫（松影はまことに武者の子孫なりと雖も）」という下りにも出てくる。