mid-15c., "that which ties or knits" in any sense, agent noun from knit (v.). Meaning "one who does knitting work" is from 1510s (c. 1300 as a surname). Occasionally knitster (1640s).
late 14c., "a fastening with a rope or thread;" mid-15c., "a joining or binding together," verbal noun from knit (v.). In Middle English also "unity; a bond, unifying force; interconnection; a relationship," but these are lost. Meaning "act of weaving a continuous thread by loops or knots" is from 1711. Meaning "knitted work, work done by a knitter" is from 1848. Knitting-needle is from 1590s.