1. A computer-implemented method for outputting a word family that includes a plurality of words, wherein each of the plurality of words is at least one of a parent word and a child word, each of the child words being formed of a combination of (a) at least a portion of its respective parent word and (b) at least one of (i) a prefix appended to the at least the portion of its respective parent word and (ii) a suffix appended to the at least the portion of its respective parent word, wherein one of the plurality of words is a root word, which does not have any parent word in the word family and has one or more child words of the word family, all others of the plurality of words at least being child words of the word family, and wherein the outputting includes presenting the word family in a hierarchical structure that includes a plurality of hierarchical levels, the root word belonging to a lowest one of the hierarchical levels, the method comprising: assigning, by a computer processor, a selected one of the plurality of words as a respective main word represented by a portion of a respective bar of a highest one of the hierarchical levels, wherein each of the hierarchical levels corresponds to a respective bar; beginning with the highest hierarchical level, and for each of the hierarchical levels, except for the lowest hierarchical level: assigning, by the computer processor, a word that is an immediate parent of the main word of the respective hierarchical level as a main word represented by a portion of the respective bar of an immediately lower one of the hierarchical levels; and assigning, by the computer processor, to remaining portions of the respective bar of the immediately lower hierarchical level, children of the word that is the immediate parent; and displaying, by the computer processor, the bars according to the assignments.
4. The method of claim 1 , wherein the portions of the bars are selectable for changing which word is the selected word.