noun
editorial; leading article; leader
Refers to an opinion piece in a newspaper or magazine that represents the publication's stance.
今朝の社説は教育改革について論じていた。
This morning's editorial discussed education reform.
論説 is a broader term for an opinion piece or commentary, not necessarily representing the official stance of a publication, whereas 社説 specifically denotes the editorial voice of a newspaper or magazine.
Compound of 社 (company, here referring to a newspaper company) and 説 (opinion, theory).