knot

Concise Oxford English Dictionary © 2008 Oxford University Press:
knot1

▶noun

• 1 a fastening made by looping a piece of string, rope, etc. on itself and tightening it.

  ■ a tangled mass in hair, wool, etc.

  ■ an ornamental ribbon.

• 2 a protuberance or node in a stem, branch, or root.

  ■ a hard mass in wood at the intersection of a trunk with a branch.

  ■ a hard lump of bodily tissue.

• 3 a small group of people.

• 4 a unit of speed equivalent to one nautical mile per hour, used of ships, aircraft, or winds.

  ■ chiefly historical a length marked by knots on a log line, as a measure of speed.

▶verb (knots, knotting, knotted)

• 1 fasten with a knot.

  ■ make (a carpet) with knots.

  ■ tangle.

• 2 cause (a muscle) to become tense and hard.

  ■ (of the stomach) tighten as a result of tension.

– phrases
at a rate of knots Brit. informal very fast.
get knotted Brit. informal go away!
tie someone (up) in knots informal confuse someone completely.
tie the knot informal get married.

– derivatives
knotless adjective,
knotter noun.

word history: Knot is first recorded in Old English in the sense ‘a fastening made in string or rope’. The link with the later (17th-century) usage as a unit of speed for ships and aircraft is made through the knotted line of the nautical device called a log (see log1). The number of knots, or length of line, that was run out in a certain time gave an estimate of the vessel's speed. There is no foundation for the attractive story that relates it to King Canute (Danish Knut), who tried to stop the tide.

Concise Oxford English Dictionary © 2008 Oxford University Press:
knot2

▶noun (pl. same or knots) a short-billed northern sandpiper. [Calidris canutus.]

– origin ME: of unknown origin.