While typing documents using gedit we can enable a very useful plugin called the autocompletion. This plugin will automatically prompt the words that have been typed previously in the document and hence save the time of retyping it.
To enable autocompletion in gedit click on
Click on the tab "plugins"
Move to the option word completion.
Enable it by checking the box on the left and close it.
Now when ever a document is being typed, gedit will automatically pop up the words that have been typed as the first letter of a word is typed. as shown below.
Please note that the autocompletion will work only on documents that have been saved and the new words that are typed will be shown in the autocompletion options only when the document has been saved after entering the new words.