The adjective biennial can express a duration and be used in connection with what lasts two years, is exercised for two years, is valid for two years, relates to a period of two years. Biennial charge. Fiscal year, biennial plan, biennial budgets.

But it can also express a periodicity and designate, perhaps more commonly, what takes place every two years. Biennial exhibition. In this sense, biennial is also used as a noun. The Venice Biennale.

Finally, biennial also designates what is done according to a two-year cycle, in the field of agriculture, for crop rotation. Biennial rotation.

Biennial is a synonym for biennial. It is therefore also used to designate what takes place every two years. Ceremony, biannual feast. Or for a plant whose development cycle lasts two years. Biennial plant. But it should not be used in the sense of “which takes place twice a year”.

The book Traps and difficulties of the French language advises against this use. We would rather say half-yearly. Semi-annual review. Semi-annual meeting. Examinations, semester payments. Or semi-annual. Semi-annual reports. The adjective semester is also used for what lasts six consecutive months. Vacation, semester course.

We will avoid the form biannual, faulty because the prefix bi becomes rather bis before a vowel, as in great-grandmother (a great-grandmother), and old words like biscuit (bis-cooked, cooked twice). The name biscuit first refers to a “slightly risen, hard and dry flour pancake”, intended for sailors and soldiers, baked twice so that it can be kept longer. In this sense, the word is used in the singular. Embark biscuit on board.

To ensure that we are understood, we may sometimes prefer a less ambiguous turn. The council meets twice a year. This activity takes place every two years. Get six months leave.

We must also avoid confusing fortnightly and bimonthly. Is a journal fortnightly or bimonthly? It comes out twice a month: it’s a fortnightly. It comes out once every two months: it’s a bimonthly.

Should the expression “the last 24 hours” be used instead of the anglicism “the last 24 hours” that we often hear, on TV, among others?

It is the construction of the last 24 hours – or the last 48 hours -, criticized, which should be avoided, in reality. We believe that we should follow the usual word order, like when we write the last 10 days (and not the last 10 days, which is modeled on English), but this is not the case.

It is because the words 24 hours (or 48 hours) form a whole here. They are considered as a unit of time. The syntagm 24 hours designates a day, the syntagm 48 hours designates two days. The adjective last should therefore not be inserted between 24 and hours. We correctly say the next 24 hours as we say the next day. This is how it should be understood. Ukrainian authorities said two people have been killed in the past 24 hours despite a ceasefire.

On his blog Notebook of a linguist, Lionel Meney gives another example that helps to understand this rule. “We say: This sportsman ran his last 100m of the season and not his last 100m, which would have a completely different meaning. »