A yarn (B') for forming filiform formations of a synthetic-grass covering reproducing the grassy sward of natural turf comprises a plurality of filiform segments (B1') set alongside one another and connected together by thin breakable connection portions (B2'), in which the filiform segments (B1') present thickened end parts. Preferably the yarn (B') is obtained by longitudinal stretching, starting from a length (B) constituted by a strip comprising a plurality of filiform segments (B1) set alongside one another and connected together by thin connection portions (B2).