Where one woman itches to tie the knot, another laps up the choices and freedom that being unattached gives her. But singlehood is a huge social problem for China. Or is it?

Whoever coined the Chinese term shengnyu a decade or so ago must have had an inkling that it was likely to offend at least half the population.

The term, meaning "leftover woman", and referring to an unmarried female in her late 20s or older, is variously defined in dictionaries as humorous or pejorative, and the choice between those two may even come down to the gender of the dictionary compiler.

But whether you love the expression or loathe it, it is likely, whenever it is wheeled out, to get Chinese talking either about demographics, if they are statistically inclined, or about love, marriage and death. The term is especially popular on reality TV shows and in soap operas.

Last year when a book about the phenomenon of singlehood was published, both of those approaches to the issue were reflected in its provocative title, Investigation into China's Leftover Women.

However, even if Chinese has come up with a concise, albeit crass, term that alludes to just one aspect of single life, China is by no means alone in having to face the issue.

In the United States among those aged 16 and above, about 130 million were single, accounting for 51.2 percent of the group, according to chinanews.com in August last year. In 1976 the rate was just 37.6 percent, it said.

China's sixth national census in 2010 showed that between 1990 and 2010 the number of unmarried women aged 25 and above increased from about 2.8 million to more than 14.5 million.

The authors of Investigation into China's Leftover Women, Luo Aiping, Wang Feng and Jiang Yu, say it was based on analyses of media reports about so-called leftover women and on qualitative studies of 43 subjects aged 27 and above from eight cities.

Many interviewees said they wanted to marry but had found no one suitable, the book says. Some said they had been through failed relationships, and some were busy with studies or a career.

Luo, who is unmarried, said she worked for two years after graduating and then did postgraduate studies. When she graduated she was 27, and for many Chinese it is a worry for a woman of that age still to be single.