Justify, justified, justification, or full justified is text that is both left-aligned and right-aligned. For example, this paragraph of text is justified. As you can see, there is no ragged edge on either the left or right side of the text. To make both sides of the text straight extra spacing is added between each of the words.
The last line of the paragraph is always left-aligned, as seen above.
The term "justify" is not a synonym for "align" or "alignment." These terms have different meanings. See the alignment definition for its meaning.