What do you call two consecutive months; a sixth of a year?
Half a year is a semester, i.e. (literally) 6 months. Since it’s often wrongly thought to derive from semi- ‘half’, there’re contradicting definitions of similar terms: Both a trimester and a (rare) quadmester are either 3 months, i.e. a fourth of a year, or a third of a year, i.e. 4 months. The definitions are mutually exclusive, that means the terms never mean the same duration in the same context. These are academic terms that usually subdivide the academic year from autumn to autumn, not the calendar year. Human pregnancies are also often divided into 3 three-month trimesters.
In economics and accounting, a quarter or quarter-year is often used, which is either defined as 3 months or as 13 weeks, i.e. 90–92 days. The possible alternative term fourth is not being used, as far as I know.
What would you call a sixth part of the calendar year, i.e. 2 collective months or about 60 days?
From other European languages, I’d assume sextal, but the OED only lists ‘base 6’ as a meaning of that word (like ‘octal’) and it’s not quartal (or tertial and quintal) in English but quarter – alas, sexter seems just wrong. Sometimes the Romance x becomes an s, and sester used to be a (Middle) English measure indeed. I could also go Greek (hexa-) instead of Latin.
I guess double-month or di-/bi-month could also work. A neologism is fine as long as it’s understandable and doesn’t raise wrong associations like a six-month span.
I think you are looking for the term bimester:
- a period of two months
(M-W)
Usage examples:
In each case they contitute an average of the responses in the October- November bimester. (Use of Survey Data for Industry, 1999.)
We proposed a bimester alternative to the trimester model. (Undergraduate Projects Linking Science, Technology and Society. )
In some cases, the simplest solution is "60 days". Or "two months".
(I've never quite understood why we get so many questions seeking single commonly known words for concepts. There is no rule saying such words have to exist, and there is nothing wrong with using a short phrase as, effectively, a compound word. Yes, seeking the perfect word is a fun game, but unless you already know it or are writing poetry, finding it is largely a distraction from actually communicating... And often the best way to find out if simply to "consult the oracular lizard of the ancient lexophile culture" and ask a thesaurus.)
According to Wikipedia, the numerical prefix corresponding to "sixth" is sextant- (which seems to be derived from the Latin word for sixth, sextans). In fact, I can't find any English word that uses this as a prefix.
But if this is accurate, it suggests the neologism sextantennium (sixth of a year) by analogy with words like millennium (thousand year period) and sesquiennium/sesquiennial (a period of one and a half years/every one and a half years, also mentioned here: Is there a term to describe an event which happens every 18 months?).
I searched for sextantennium on Google and found zero results. Personally, I'd go with Josh61's suggestion of bimester.
Another related question:
- word for six-month period.....not as an adjective or as an associated adverb, but as an affirmed set word