plain knit

noun
  1. the simplest knitted construction, consisting of vertical ribs visible on the front of the fabric and horizontal rows of stitches visible on the back, used in the production of hosiery and jersey fabrics.

Origin of plain knit

First recorded in 1965–70
Also called flat knit.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018