Derived from the preposition op (“on, upon”), which also has an adverbial sense “open”, as has German auf. The infix -en- may stem from the older affen (“open”), from Old High German offan, which itself is cognate with German offen, Dutch open, and English open. (The phonetic similarity between Luxembourgish oppen and Dutch/English open is thus accidental.) Other dialects of Moselle Franconian and Ripuarian generally use the stem opp- (without -en-) for the adjective “open”.
oppen (masculine oppenen, neuter oppent, not comparable)
| number and gender | singular | plural | |||
|---|---|---|---|---|---|
| masculine | feminine | neuter | all genders | ||
| predicative | hien ass oppen | si ass oppen | et ass oppen | si si(nn) oppen | |
| nominative / accusative |
attributive and/or after determiner | oppenen | oppen | oppent | oppen |
| independent without determiner | oppenes | oppener | |||
| dative | after any declined word | oppenen | oppener | oppenen | oppenen |
| as first declined word | oppenem | oppenem | |||
oppen