  The noun lexica of many natural languages are divided into several declension
classes with characteristic morphological properties. Class membership is far
from deterministic, but the phonological form of a noun and/or its meaning can
often provide imperfect clues. Here, we investigate the strength of those
clues. More specifically, we operationalize this by measuring how much
information, in bits, we can glean about declension class from knowing the form
and/or meaning of nouns. We know that form and meaning are often also
indicative of grammatical gender---which, as we quantitatively verify, can
itself share information with declension class---so we also control for gender.
We find for two Indo-European languages (Czech and German) that form and
meaning respectively share significant amounts of information with class (and
contribute additional information above and beyond gender). The three-way
interaction between class, form, and meaning (given gender) is also
significant. Our study is important for two reasons: First, we introduce a new
method that provides additional quantitative support for a classic linguistic
finding that form and meaning are relevant for the classification of nouns into
declensions. Secondly, we show not only that individual declensions classes
vary in the strength of their clues within a language, but also that these
variations themselves vary across languages.
