Why do French -ir verbs follow two different patterns?

One ending, two conjugation patterns

When learners first meet French verbs, the infinitive looks like the obvious clue. Verbs ending in -er mostly behave alike, so it is reasonable to expect the same from verbs ending in -ir. But compare these two present-tense patterns:

The difference is not a random exception added to modern French. It is the result of centuries of sound change, reorganisation and analogy. To understand it, we must separate three things that do not always coincide:

• etymology: where a word came from;
• meaning: what the verb expressed at a particular time;
• conjugation: the pattern its forms follow.

Latin did not have the French three-group system

Traditional Latin grammar distinguishes four regular conjugations, usually identified by the infinitive. The macrons and breve below show vowel length: ē is long and ĕ is short.

This immediately reveals something surprising: Latin finīre and dormīre belonged to the same conjugation. Their French descendants—finir and dormir—do not.

How did Latin -sc- become French -iss-?

Latin could add the element -sc- to certain verbs. In many cases, it gave the verb an inchoative meaning: it presented the beginning of a process or entry into a new state. For example, Latin caleō meant “I am warm,” while calēscō meant “I become warm.”

During the development of spoken Latin and the Romance languages, forms containing -ēsc- or -īsc- became associated with verbs in -īre. After phonetic changes and a broader reorganisation of verb patterns, this old sequence contributed to the French -iss- seen in forms such as fleurissons, finissons and grandissant.

The crucial change is that an element once connected with meaning became a grammatical feature. In modern French, nous finissons does not mean “we are beginning to finish.” The -iss- simply belongs to the verb’s conjugation.

Why did finir adopt this pattern?

Finir comes from Latin finīre, related to fīnis, “limit” or “end.” Its Latin source was not an infinitive in -iscere. The verb therefore shows the role of analogy: speakers reshape forms by connecting them with an established pattern.

Once the -iss- model had become strong and recognisable, it could attract verbs whose individual histories were different. The conjugation class was no longer limited to verbs that had carried an inchoative meaning in Latin.

Choisir: a Germanic word in the same French group

Choisir makes the point even more clearly. It is not inherited from a Latin -īre verb at all. The word is of Germanic origin and is connected with Gothic kausjan, “to taste, examine or test.” Old French coisir first meant “to distinguish” or “to see clearly” before developing the modern meaning “to choose.”

Yet today we say nous choisissons and choisissant. A Latin inheritance and a Germanic word have entered the same French conjugation pattern.

Why are partir and dormir different?

Not every French verb in -ir adopted the expanding -iss- model. Dormir, from Latin dormīre, developed forms without it: je dors, nous dormons, dormant. Partir, from Latin partīre, followed another pattern: je pars, nous partons, partant.

This does not mean that these verbs remained unchanged from Latin. Their sounds, stems and meanings evolved too. What matters is that they did not join the particular pattern now represented by finir.

The traditional third group is therefore not one uniform historical family. It is a convenient category that gathers verbs which do not belong to the two large regular models represented by aimer and finir.

An Italian cousin: finire / finisco

Italian preserves a particularly visible relative of the same historical development. The verb finire gives io finisco and tu finisci. The element -isc- is still easy to recognise.

French and Italian did not distribute the inherited element in exactly the same places, but the comparison helps make the Romance history visible.

How do you recognise a French second-group verb today?

For modern French, you do not need to reconstruct the verb’s history. Use this practical test:

You can also look at the nous form in the present: nous finissons, nous choisissons, nous grandissons. By contrast, partant, dormant, venant and ouvrant show that those -ir verbs do not belong to this regular pattern.

Some second-group verbs still describe a transformation: rougir means “to turn red,” grandir “to grow,” and vieillir “to grow old.” But meaning alone cannot identify the group. Choisir belongs to it without expressing a change of state, while s’endormir expresses entry into sleep and belongs to the third group.

Mini practice: follow the pattern

Frequently asked questions