a collection of items organized hierarchically where, if we assume the root is at level 0, a node at level is associated with the i-th character of the key. The branching ratio is high, and efficient lookup of words is possible if compression of the data structure does not unduly slow search.
a data structure similar to but different to a tree
a data structure that stores an associative array with string-valued keys
a digital search tree in which leaves correspond to records in a file