noun

• (architecture) A finial, or swelling termination
  "In the three upper elements, the knop-finial-fillet, both masters use all three squares from the base plan forming widths of 1:2:√2 (another pleasing rhythm). In the gable over the window the finials have width in the ratio of √2:4:2. The elements on the pinnacle relate to those on the gable as 1:√2, 1:2 and √2:2."
• (sewing) A tuft or overthickened bunch of looped or twisted yarn
  "The thick places are created by winding effect yarn around the core yarn. We can distinguish the length of the knop L, its thickness D, the distance between them Q, and the nominal diameter of continuously twisted component yarns d. The sum of the distance between the knops and the length of a knop is the stitch of this kind of fancy yarn."
• (botany, art) A closed bud or bud-like, swelling protuberance of a plant, or the representation thereof in the decorative arts
  "On these shawl borders the knop and flower are often also combined, the knop becoming the cone or Cypress-like trunk of a tree, the branches of which fam out like the fronds of the Hom. [Plate III., fig. 6]. In some Indian and Persian carpets the knop or cone throws out graceful Hom fronds, one on either side, from the ends of which hangs a large flower, presenting the alternation of a branching cone and flower."