Definition of "yf"

yf¹

conjunction
1. Obsolete form of if.

yf²

phrase
1. (knitting) Initialism of yarn forward.
  Quotations
  Row 3. P1, yb, sl1 purlwise, yf, pbf, p1.
  1997, Jo Sharp, Knitted sweater style: inspirations in color, page 62