From Middle Dutch onweder, from Old Dutch *unwedar, from Proto-Germanic *unwedrą. Equivalent to on- + weer, literally "unweather". Cognate with Old English unweder, German Unwetter, Swedish oväder.
onweer n (plural onweren, diminutive onweertje n)
- (often uncountable) thunderstorm
- first-person singular present indicative of onweren
- imperative of onweren