errant

Concise Oxford English Dictionary © 2008 Oxford University Press:
errant /ˈɛr(ə)nt/

▶adjective

• 1 formal or humorous erring or straying from the accepted course or standards.

• 2 archaic or literary travelling in search of adventure. See also knight errant.

• 3 Zoology (of a polychaete worm) of a predatory kind that moves about actively and is not confined to a tube or burrow.

– derivatives
errancy noun,
errantry noun.

– origin ME: sense 1 from L. errant-, errare ‘err’; sense 2 from OFr. errant ‘travelling’, pres. part. of errer, from late L. iterare ‘go on a journey’, from iter ‘journey’.