plowshare Syllabification: (plow·share)Pronunciation: /ˈplouˌSHe(ə)r/ (British ploughshare)Definition of plowshare noun the main cutting blade of a plow, behind the coulter. Origin: late Middle English: from plowgh, an earlier spelling of plow + Old English scær, scear 'plowshare' (related to shear)plowshare in other Oxford dictionaries Definition of plowshare in the British & World English dictionary