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88. The Stem of nouns of the 4th Declension end in u-. This is usually weakened to i before -bus. Masculine and feminine nouns form the nominative by adding s; Neuters have for nominative the simple stem, but with ū (long).

89. Nouns of the Fourth Declension are declined as follows.

Paradigm for 4th declension nouns

90. Most nouns of the 4th Declension in -us are masculine.


The following are feminine:

acus, anus, colus, domus, īdūs (plural), manus, nurus, porticus, quīnquātrūs (plural), socrus, tribus

with a few names of plants and trees. Also, rarely, penus, specus.

91. The only neuters of the 4th Declension are:

cornū, genū, pecū (see § 105.f), verū1



1. A few other neuters of this declension are mentioned by the ancient grammarians as occurring in certain cases.

Suggested Citation

Meagan Ayer, Allen and Greenough’s New Latin Grammar for Schools and Colleges. Carlisle, Pennsylvania: Dickinson College Commentaries, 2014. ISBN: 978-1-947822-04-7.