Let a cotree of a spanning tree 
in a connected graph 
be denoted 
. Then the edges of 
which are not in 
are called its twigs (Harary 1994, p. 39).
Twig
See also
CotreeExplore with Wolfram|Alpha
References
Harary, F. Graph Theory. Reading, MA: Addison-Wesley, 1994.Referenced on Wolfram|Alpha
TwigCite this as:
Weisstein, Eric W. "Twig." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Twig.html