Such a form contains the main idea of the word in a very general sense, and is common also to other words either in the same language or in kindred languages.[For example, the root STA is found in the Sanskrit tishth=ami, Greek isthmi, Latin sistere and stáre, German stehen, and English stand.]
Thus the root of the stem vóc- is VOC, which does not mean to call, or I call, or calling, but merely expresses vaguely the idea of calling, and cannot be used as a part of speech without terminations. With á- it becomes vocá-, the stem of vocáre (to call); with áv- it is the stem of vocávit (he called); with áto- it becomes the stem of vocátus (called); with átión- it becomes the stem of vocátiónis (of a calling). With its vowel lengthened it becomes the stem of vóx, vócis (a voice: that by which we call). This stem vóc-, with -ális added, means belonging to a voice; with -ula, a little voice.
NOTE: In inflected languages, words are built up from Roots, which at a very early time were used alone to express ideas, as is now done in Chinese. Roots are modified into Stems, which, by inflection, become fully formed words. The process by which roots are modified, in the various forms of derivatives and compounds, is called Stem-building. The whole of this process is originally one of composition, by which significant endings are added one after another to forms capable of pronunciation and conveying a meaning.
Roots had long ceased to be recognized as such before the Latin existed as a separate language. Consequently the forms which we assume as Latin roots never really existed in Latin, but are the representatives of forms used earlier.