A "Sugar Daddy" is a wealthy (and usually older) man who supports and provides for a younger woman in exchange for companionship and/or other favors.
Example of use: Rachel — "Did you see Dana's new diamond ring?", Kelly—"Don't you know, her new sugar daddy bought it for her. I can't believe her, he is the same age as her father".
The word 'Sugar' has been a slang word for money and luxury since the mid-19th century, and defines the nature of the relationship between the couple. The word 'Daddy' was slang among prostitutes for an older man since the 16th century, and refers to the age difference between the two. The term "Sugar Daddy" has been used since the beginning of the 19th century, when Adolph Spreckels, heir to the Spreckel's sugar fortune, married a woman who was 24 years younger than him and called him "Sugar Daddy". However, the first recorded use was in 1923 in the Syracuse Herald in an episode of the story "Fat Anna's Future".