I am a dictionary

I am a dictionary
Of me you need not be wary
I, a helping hand will lend
When any word you cannot comprehend.
If you are looking for a word's ancestry
I can give you its family history
When spelling has you floundering
Precious assistance you will find me rendering.
If a word you find difficult to utter
You can depend on me to be your guider
Seldom will you find anyone so brainy
Coz I can solve all your word query.