tree
undirected, connected and acyclic graph
spanning tree
subgraph of an undirected graph G that is a tree which includes all of the vertices of G
caterpillar tree
tree in which all the vertices are within distance 1 of a central path
centered tree
tree graph with only one center
starlike tree
tree graph with exactly one vertex of degree >2
skill tree
game mechanic
technology tree
diagram used in strategy computer games
free tree
connected, acyclic, undirected graph without a designated root node
rooted tree
directed tree in which one vertex has been designated the root