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half-birthdayalso half birthday

noun [countable]

a day which is exactly six months before or six months after the actual day a person was born

'It's happy half birthday to the first of 76 million baby boomers who turned 59½ on Friday and can take money out of their retirement accounts without paying a 10 percent early-withdrawal penalty …'

The Sun Herald 3rd July 2005

Do you need an excuse for a celebration, because Christmas and your birthday are still a few months away? If so, then why not think about celebrating your half-birthday – the day that falls exactly six calendar months either before or after your real date of birth. If you were born on 27th January for instance, you could have an excuse for a party on Wednesday 27th July (if you count the months) and on Friday 29th July (if you count the days)!

the concept is most commonly adopted by people whose real birthday is likely to be overshadowed by other major events, especially Christmas – so half-birthday celebrations are more common in June or July

On 1st July 2005, the concept of a half-birthday was of particular financial significance to millions of American baby boomers (people born in the baby boom following the end of World War II). On 1st July, anyone born on 1st January 1946 would be celebrating their 59½ birthday, and therefore legally entitled to withdraw money from their tax-free Individual Retirement Account without paying a ten percent 'early-withdrawal' penalty – the very first group of baby boomers to be able to do this.

The majority of half-birthdays pass without this kind of significance however, and usually go uncelebrated. The concept is most commonly adopted by people whose real birthday is likely to be overshadowed by other major events, especially Christmas – so half-birthday celebrations are more common in June or July. In the United States, half-birthdays are often celebrated for young children whose real birthdays do not fall within the school year, thus giving them the opportunity to celebrate in school with their friends and teacher.

If you'd like an excuse for a celebration and want to know when your own half birthday falls, you can find out by entering your dates into this half-birthday calculator.

Background – half-birthday

Though the concept of a half birthday has been acknowledged for many years – the simple idea of being half a year older – use of the expression itself has gained currency more recently by featuring in the Harry Potter series of books by J. K. Rowling, the latest of which was published on 16th July 2005. During their adventures, Harry's friends try to cheer him up by celebrating his half birthday on January 31st.

A half birthday could also be referred to as an unbirthday, just another one of the 364 days in a year which are not a person's real birthday. The word unbirthday (a combination of birthday and the prefix un-, meaning 'not'), was coined by author Lewis Carroll in the classic children's novel Through the Looking Glass, and featured in a song from the Walt Disney film version Alice in Wonderland.

by Kerry Maxwell, author of Brave New Words

This article was first published on 18th July 2005.

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