Inherited from Middle French aigu, agu, from Old French agu, from Latin acūtus (“sharp”); related to English acute. The original Old French result was eü (preserved in the toponym Montheu < Latin Mons acutus (“sharp mountain”)), which was likely modified into the form agu based on the Latin, and then influenced by words like aigre, or aiguiser, as with aiguille.
aigu (feminine aiguë or aigüe, masculine plural aigus, feminine plural aiguës or aigües)
From Proto-Finnic *aika. Cognates include Finnish aika and Karelian aika.
aigu
| Declension of aigu (Type 3/jalgu, ig-ij gradation) | ||
|---|---|---|
| singular | plural | |
| nominative | aigu | aijat |
| genitive | aijan | aijoin |
| partitive | aigua | aigoi |
| illative | aigah | aigoih |
| inessive | aijas | aijois |
| elative | aijaspäi | aijoispäi |
| allative | aijale | aijoile |
| adessive | aijal | aijoil |
| ablative | aijalpäi | aijoilpäi |
| translative | aijakse | aijoikse |
| essive | aijannu | aijoinnu |
| abessive | aijattah | aijoittah |
| comitative | aijanke | aijoinke |
| instructive | aijoin | |
| prolative | aijači | |
From French aigu (“sharp, acute”), from Middle French aigu, agu (“sharp”), from Old French agu, from Latin acūtus (“sharpened, spicy, subtle”), perfect passive participle of acuō (“I sharpen, put an acute accent on”), from acus (“needle, pin; bodkin”), from Proto-Italic *akus, from Proto-Indo-European *h₂eḱus, from *h₂eḱ- (“sharp”).
aigu m (definite singular aiguen, indefinite plural aiguer, definite plural aiguene)