Le temps qui passe

French has two words for several units of time, and the difference is not decorative. An and année both mean year. Jour and journée both mean day. So do soir and soirée, matin and matinée.

The test that works

If a bare number goes in front of it, use the short one. Once an adjective joins the number, the long one usually comes back: deux longues années, trois belles journées.

• Deux ans, trois jours, cinq matins
• Une bonne année, toute la journée, une longue soirée

The short form counts the unit. The -ée form describes the span you lived through, its texture and contents. J'ai passé trois jours à Paris counts them off. J'ai passé une journée formidable tells you what the day was like.

Where it bites

Birthdays and ages take an, always: il a trente ans. Say trente années and you have described thirty years as a stretch of experience, which is a strange thing to do to somebody's age.

New Year is the exception that everyone meets first: bonne année, not bon an. You are wishing them a whole year of content, not counting one.

Bonsoir and bonne soirée

Bonsoir greets someone in the evening, and it works as a goodbye too, on your way out after dark. Bonne soirée is only for leaving, wishing them a good evening ahead. So the slip to avoid is bonne soirée as you walk in, which sounds as though you are leaving as you arrive.

The same split runs through the day: bonjour on arrival, bonne journée on departure.

Two more worth having

Fois is time in the sense of occasion: une fois, deux fois, la première fois. It never means duration.

Temps is time in the abstract, and also the weather, which trips people up for about a week and then stops being a problem. Je n'ai pas le temps is I do not have time. Quel temps fait-il ? is what is the weather doing.