Most of the approximately 5,000 words in the Greek NT have the ability to vary their meaning through change of form. Change of form can include changing number (singular or plural) and - in the case of a verb - person (I, you, he, we, you or they) and time (present, past or future). In Dutch, for example, "loop, loopt, lopen, lopend, ran, walked, walked, gelopen" are all word forms to the one word "walk.

The different forms a word can take to vary its meaning are called "word forms. One of the word forms is established as a "keyword form," that is, the word form used to list the word in its alphabetical place in a dictionary. When, exceptionally, a word changes its form for reasons other than to vary its meaning, the different forms are not considered different word forms according to this definition: of word 4598 hupo, for example, the 'form' hup, which results from omitting the last vowel before a subsequent word beginning with a vowel, is not considered a separate word form.

The words that can vary their meaning by changing their form belong to the following word types: article, numeral, adjective, noun, pronoun and verb. The word types of adverb, conjunction, preposition, particle and interjection cannot change their form to vary their meaning; thus, a word in these word types has only one word form, which then naturally must also be used as a keyword form.

Many names of non-Greek origin remain unchanged because they are not adapted to the Greek language system. These are classified as inflectional (unverb.).

To properly understand the meaning of a single word form, it is necessary to have an overview of all word forms of the same word that can occur in addition to this one form. An orderly division into types of word forms is that in noun and verb.

In the representation of word forms, each word form is labeled with a number one and translation.