Unknown. Compare Finnish haura (“pondweed”), dialectal hatru, which may or may not have been borrowed from Estonian.
adru (genitive adru, partitive adrut)
| Declension of adru (ÕS type 16/pere, no gradation) | |||
|---|---|---|---|
| singular | plural | ||
| nominative | adru | adrud | |
| accusative | nom. | ||
| gen. | adru | ||
| genitive | adrude | ||
| partitive | adrut | adrusid | |
| illative | adrusse | adrudesse | |
| inessive | adrus | adrudes | |
| elative | adrust | adrudest | |
| allative | adrule | adrudele | |
| adessive | adrul | adrudel | |
| ablative | adrult | adrudelt | |
| translative | adruks | adrudeks | |
| terminative | adruni | adrudeni | |
| essive | adruna | adrudena | |
| abessive | adruta | adrudeta | |
| comitative | adruga | adrudega | |
From Proto-Finnic *atra (compare Estonian ader, Finnish aura), from a Germanic language (compare Old Norse arðr), from Proto-Germanic *arþrą, from Proto-Indo-European *h₂érh₃trom.
adru
| Declension of adru (Type 3/jalgu, no gradation) | ||
|---|---|---|
| singular | plural | |
| nominative | adru | adrat |
| genitive | adran | adroin |
| partitive | adrua | adroi |
| illative | adrah | adroih |
| inessive | adras | adrois |
| elative | adraspäi | adroispäi |
| allative | adrale | adroile |
| adessive | adral | adroil |
| ablative | adralpäi | adroilpäi |
| translative | adrakse | adroikse |
| essive | adrannu | adroinnu |
| abessive | adrattah | adroittah |
| comitative | adranke | adroinke |
| instructive | adroin | |
| prolative | adrači | |