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.
User Defined Definitions
"a tight cluster of people or things"
"a hard cross-grained round piece of wood in a board where a branch emerged"
"something twisted and tight and swollen"
"soft lump or unevenness in a yarn; either an imperfection or created by design"
"a sandpiper that breeds in the Arctic and winters in the southern hemisphere"