Young and old people actually experience completely different emotions when they say they are "happy", says a new study.
The research found that for younger people, about 60 percent of happiness is based on feelings of excitement.
However, for older people, 80 percent of happiness corresponded with levels of contentment.
"We are talking about two distinct types of happiness, one associated with peacefulness and one associated with being excited," the Daily Mail quoted Professor Cassie Mogilner of the University of Pennsylvania as saying.
"Whereas younger people are more likely to associate happiness with excitement, as they get older, they become more likely to associate happiness with peacefulness," she stated
The difference appears to come from the varying degrees of importance placed on the future compared to the present.
Younger people, generally more interested in the future, base their happiness more on excitement, said Prof Mogilner, a professor of marketing.
Meanwhile, older people place a higher value on the present, and so contentment tends to be a greater source of happiness for them.
The results were published in the journal Social Psychological and Personality Science.