Q: I was about to call you at WNYC about the misuse of the term “decade,“ when I was serendipitously beaten to the punch by a gentleman who seemed to read my mind! I think you were quite dismissive, though, after he pointed out that it was wrong to refer to the present year as the start of a new decade. I’ve always believed a decade begins with a year ending in one, as in “this is year one.” Am I suffering from a case of digititis?
A: I’m sorry if I sounded dismissive, but this is an argument that I’ve been unwillingly drawn into time after time and it is, at bottom, a rather silly one.
A child is not born on his first birthday. He lives his first year from age 0 (birth) until his first birthday. He officially becomes 1 year old just as he is entering his second year.
Years later, we say he is in his 30th year when in fact he’s 29. When he celebrated his 29th birthday (meaning 29 years had elapsed since his birth), he entered his 30th year.
Similarly, this is why we describe the 1400s as “the 15th century.” Same principle: the clock starts at zero.
So the first year of each decade is completed on Dec. 31 of the zero year. In other words, the first year begins with 0 and ends with 1. The second year begins with 1 and ends with 2, and so on.
The tenth year of the decade begins with 9 and ends with 10 (at which point we’re back to a year ending in zero). On to the second decade, which begins with 10; the third begins with 20, etc.
The first year of the first millennium – for our purposes, we can call it “year 0″ – ran from 1 BC to AD 1, because technically there is no recognized “year 0″ in Western calendars (though there is in astronomical calendars).
In this case, the clock started at 1 BC, which becomes our “zero.”
Counting years is not like counting fingers. When counting years or decades, we call the first one “zero” and the 10th one “nine.”
Would you say the 1950s began with 1951 and continued through the end of 1960? Of course not. Common sense tells us that the ten years we call the 1950s began in 1950 and continued through the end of 1959.
Having said that, I must add that arguing endlessly about what we call a decade is rather silly. A “decade,” by definition, is ANY 10 years.
In fact, the word “decade” (from the Latin decas and ultimately the Greek dekas, “ten”) meant 10 of anything when it entered English in the 1400s, just as a dozen now means 12 of anything.