German words ending in -tum
A noun built with -tum is das, and the two that are not are short enough to memorise now.
-tum builds abstract nouns out of other nouns and adjectives. Eigen gives das Eigentum, wachsen gives das Wachstum, Christ gives das Christentum, Volk gives das Volkstum. The plural takes an umlaut and -tümer, a useful signal that you are looking at the suffix and not at something else.
Two nouns break it: der Reichtum and der Irrtum are masculine. That is the entire exception list, so learn the pair as a unit and the rule is closed.
Separately, plenty of German nouns end in -um without carrying this suffix at all. Datum, Museum, Zentrum and Album are Latin, not Germanic, and their -um is part of the borrowed word. They happen to be neuter as well, so guessing das still works, but they are a different ending and their plurals behave differently.
Worked examples
- das Eigentum property not in the deck, unchecked
- das Wachstum growth not in the deck, unchecked
Not in this deck
This deck holds no noun built with -tum. The one word in it that reaches those letters is Datum, and that is Latin, counting against -um instead, so it is listed below as a look-alike rather than as evidence. The rule here stands on German, not on a count.
Looks like it, is not
One word in the deck ends in these letters without being built from the suffix, and it is the one most likely to mislead you.
- das Datum die Daten
Try it
The drill below is the mixed deck, and it holds no -tum noun at all. It does hold a Latin -um word, and the article comes out the same either way. That is luck rather than a rule.
Wohnung