cast-on noun 3cast on verb 1forms 5 noun3 •The act of casting on. •The technique of starting knitting by casting on. •The resulting row of cast-on stitches. cast on verb1 •To start the first row of knitting by putting stitches on a needle.Cast on 100 stitches; knit back plain. — 1878 formscasted on · casting on · casts on · cast ons · cast-ons