knot

Definitions
Examples

(noun): A looping of a piece of string or of any other long, flexible material that cannot be untangled without passing one or both ends of the material through its loops.
(noun): (of hair, etc) A tangled clump.
(noun): A maze-like pattern.
(noun): A non-self-intersecting closed curve in (e.g., three-dimensional) space that is an abstraction of a knot (in sense 1 above).
(noun): A difficult situation.
(noun): The whorl left in lumber by the base of a branch growing out of the tree's trunk.
(noun): Local swelling in a tissue area, especially skin, often due to injury.
(noun): A protuberant joint in a plant.
(noun): Any knob, lump, swelling, or protuberance.
(noun): The swelling of the bulbus glandis in members of the dog family, Canidae
(noun): The point on which the action of a story depends; the gist of a matter.
(noun): A node.
(noun): A kind of epaulet; a shoulder knot.
(noun): A group of people or things.
(noun): A bond of union; a connection; a tie.
(noun): A unit of speed, equal to one nautical mile per hour. (From the practice of counting the number of knots in the log-line (as it is paid out) in a standard time. Traditionally spaced at one every 1/120 of a mile.)
(noun): A nautical mile
(noun): The bulbus glandis
(noun): In omegaverse fiction, a bulbus glandis-like structure on the penis of a male alpha, which ties him to an omega during intercourse.
(verb): To form into a knot; to tie with a knot or knots.
(verb): To form wrinkles in the forehead, as a sign of concentration, concern, surprise, etc.
(verb): To unite closely; to knit together.
(verb): To entangle or perplex; to puzzle.
(verb): To form knots.
(verb): To knit knots for a fringe.

Climbers must make sure that all knots are both secure and of types that will not weaken the rope.
The nurse was brushing knots from the protesting child's hair.
A knot can be defined as a non-self-intersecting broken line whose endpoints coincide: when such a knot is constrained to lie in a plane, then it is simply a polygon.
I got into a knot when I inadvertently insulted a policeman.
When preparing to tell stories at a campfire, I like to set aside a pile of pine logs with lots of knots, since they burn brighter and make dramatic pops and cracks.