Is this definition of calendar year wrong?

There is a distinction between calendar year, sidereal year, and solar year, also.

At work, this year = this fiscal year. Adding “calendar” adds quite a bit to the word year.

I have never come across “calendar year” meaning anything other than the period from January 1 to December 31.

That’s distinguished from “fiscal year,” which for Thailand is the period from October 1 to September 30.

This. A calendar year is a year as measured by the calendar - a period of either 365 or 366 days, but it can start on any day. Thus the period from (say) 10 March 2016 to 9 March 2017 is a calendar year, though not a sidereal year or a solar year.

Context can modify this. If I contrast calendar year with fiscal year, financial year or academic year, then I probably mean the year starting on 1 January and continuing until the next 31 December. And of course if a particular year is specified (“calender year 2016”) that certainly means the year beginning on 1 January. And I think that in practice the term calendar year is mostly used in these contexts.

A calendar year is that range of dates designated as being within the same “year” as per the calendar, that is, a period starting on Jan. 1 and ending on Dec. 31 and when written using the common dating st system occurs within the same designated “year,” such as “2016.”

Perzactly.

The only usage I’ve seen it is in contrast with a fiscal year or a school year where the starting dates are not Jan. 1.

I don’t see why someone would use the phrase “calendar year” to mean, well, you know, a year.

If want to refer to a year you say “this year”, “2015”, etc. The whole point of saying “calendar year” is to refer to a 12 month period in general.

E.g., the IRS has rules like having to start taking RMDs from your IRA the year you turn 70 1/2. They don’t say “the calendar year you turn 70 1/2” as that would imply you can start at any point before your turn 71 1/2.

Good point, and interesting, different mode of analysis of the query from the other posts.

FWIW, as a non-businessman specifically, but playing one on the IRS Channel, I have always understood that in normal day to day discourse (we who don’t talk about solar time, etc.) there is a fiscal year and a Jan-Dec year.

Exactly the opposite. A “year” without qualification is a measured period of time that can start from any point. A “calendar year” is specifically a year that starts and ends according to s calendar.

In many cases “calendar” might not be necessary to specify because your intent is unambiguous. It becomes necessary, for example, when your audience might be unsure whether you are referring to a government it corporation’s fiscal year (which often begins in September) or whether you’re referring to the calendar year beginning Jan. 1.

But how long is the period? 365 days? 366 days? 365.25 days? Some other even more precisely defined time?

“Calendar year” is one possible answer to that question. It’s a year as measured by the calendar. It can start on any day, and it can be either exactly 365 days long or 366 days long, and you’ll need to consult a calendar to find out which.

Not if we’re talking about taxes and the IRS. Calendar year means 1/1 to 12/31 and nothing else. A fiscal year means a beginning and end on any other month, but still the start of the months. There are short years, such as a company might have if it incorporated today - it might have a short year from 3/11/16 to 12/31/16. There are even 52/53 week years for companies that insist on ending each year on the same day of the week.

Of course, IRS and legal language is also generally a lot more precise than these simpler terms. It might say “For taxable years beginning on or after 1/1/16…” so that we’re clear about every single kind of year that might be relevant.

Sure. I have already acknowledged that in particular contexts “calendar year” indicates the January/December year - particularly when “calendar year” is used in contrast to “academic year”, “fiscal year”, “tax year”, “financial year”, etc. And I have also acknowledged that in practice the term is used in contexts such as these more often than not.

But, absent such a context, the term itself is not inherently limited to the January/December year. The year is a cycle, and the whole point of a cycle is that you can start at any point, and you’ll eventually get back to that point; therefore there is no fixed start or finish point. Any period of a year, as measured by a calendar, is a calendar year, just like any period of a year, as measured by the apparent position of the sun in the sky, is a solar or tropical year, and any period of a year, as measured by the position of the sun with respect to the fixed stars, is a sidereal year.

“Calendar year” doesn’t answer that question, because some calendar years are 365 days long and some are 366 days long. The point of referring to the calendar is because a calendar is for a specific record year, such as 2016, and it always starts on Jan. 1 and ends on Dec. 31. There are no commonly used calendars that are ordinarily referred to for business purposes that start and end on any other days.

It’s simple convention that we (mostly) print calendars for one year only. And, for what it’s worth, we do print calendars that start other than on 1 January; you can easily find an academic year calendar or a financial year calendar, for example.

But whether a particular period is a calendar year or not isn’t determined by whether somebody has found it commercially viable to print a calendar covering that exact period. All printed calendars are simply extracts from the calendar. If you open Outlook you’ll find that the calendar stretches indefinitely in both directions. (OK; the Outlook calendar won’t in fact go back before 1 April 1601, and it may have an equally arbitrarily-chosen future date beyond which it won’t go, but you take my point.) If you want to know how many days will elapse between 9 June 2099 and 8 June 2100 the calendar will tell you.

And we call those an “academic year calendar” and a “financial year calendar” and when we refer to those periods of time, we call them the “academic year” and the “financial year.”

And a computerized calendar that stretches out infinitely in both directions is a recent invention. It’s a tool that exists, but it has nothing to do with the term “calendar year.” That term specifically refers to the customary 12-month calendar that starts on Jan. 1. and whose dates are all part of the same historical year that is designated as a year in our dating system—that’s exactly what a “calendar year” is.

Computerisation may be a recent invention, but the calendar certainly isn’t. The calendar as a concept predates both the computer and the production of printed extracts from the calendar. And the conceptual calendar does indeed stretch indefinitely.

Come at this another way. Is the period from 9 June 2099 to 8 June 2100, both dates inclusive, a year? I think most people would say yes. Is it a solar year? No. Is it sidereal year? No. So what makes you say it’s a year? Well, it’s a year long as measured by the calendar. Therefore, it’s a calendar year, as opposed to any other kind of year.

Can you find a single usage of that definition on the Internet?

We aren’t talking about high level concepts here. We are talking about usage. And people use calendar year to mean 2014, 2015, 206, etc., not any period of the length of a year. That’s just what it means when people say it.

Language is not math. Words mean what people use them to mean, not based on deduction. You can insist on your scientific definition of the term but when you step outside the bobble of that specialized usage you’re going to have to use it in a way that people are familiar with it you’re going to have to continuously explain yourself.

Well, as has been pointed out earlier in this thread, descriptive dictionaries confirm that the term is used in both senses. And that conforms to my own experience. It may not conform to you experience, but why should your experience be normative?

Plus, I have to note that you qualify your own arguments by reference to context. You point out that the term has the Jan/Dec sense “if we’re talking about taxes and the IRS”, and you construct an argument on the basis that “there are no commonly used calendars that are ordinarily referred to for business purposes that start and end on any other days”. Leaving aside th fact that the second statement is false - calendars commencing on days other than 1 Jan are routinely used for business purposes - doesn’t the fact that you felt the need to qualify your case in this way indicate some awareness that , outside the tax/business context, the term is indeed used more flexibly?

I’ll cheerfully concede that, overall, it’s probably used more often in the Jan/Dec sense. But that doesn’t make the other sense wrong. The OP asks about the definition of the term, not its usage. And a definition, to be complete, has to cover the various senses in which the term is used.