The most selfish ONE letter word - I
The most satisfying TWO letter word - WE
The most poisonous THREE letter word - EGO
The most used FOUR letter word - LOVE
The most pleasing FIVE letter word - SMILE
The fastest spreading SIX letter word - RUMOUR
The hardest working SEVEN letter word - SUCCESS
The most enviable EIGHT letter word - JEALOUSY
The most powerful NINE letter word - KNOWLEDGE
The most essential TEN letter word - CONFIDENCE