Year Division by Quarters: any terms to express halves of years or other parts of years?

Quarters divide years by four. I am looking for the terms dividing years by 2, 3 and 6.

Does there exists terms to express other parts of the years like quarters?

Yes, a quarter, or trimester is a period of 3 months (a quarter year).

Quarter: one fourth of a calendar or fiscal year: The bank sends out a statement each quarter.(http://www.dictionary.com/browse/quarter)

Trimester: a period of three or about three months; especially :any of three periods of approximately three months each into which a human pregnancy is divided https://www.merriam-webster.com/dictionary/trimester

A semester is a period of six months (half a year).

Semester :a period of six months https://www.merriam-webster.com/dictionary/semester

A bimester is a sixth of a year (two months).

Bimester :a period of two months

A tertile or quadrimester is four months (a third of a year).

Quadrimester: A period of four months http://www.definition-of.com/quadrimester

Tertile: 1. (statistics) Either of the two points that divide an ordered distribution into three parts, each containing a third of the population. 2. (statistics) Any one of the three groups so divided. The first tertile results include January through April's revenues. https://en.wiktionary.org/wiki/tertile

In American business usage, particularly in financial reports, the year is divided into either months or quarters. No other division is common enough to have been given a name except for half. "That merger is scheduled to close in the first half."

"Semester" and "trimester" are primarily, perhaps exclusively, academic terms and refer to divisions of a "school year," which is not generally 365 days. I cannot remember hearing those terms ever used in a commercial or financial context.

It is of course possible to find special terms, but they are not in frequent use. What is usually done is to specify a fraction of a year or a number of days, weeks, or months. One might say "a third of a year" or "four months." Fractions using sixths or twelfths are rare. Most would say "seven months" rather than "seven twelfths of a year."