The Vowel Declension is commonly called the Strong Declension, and its nouns Strong Nouns.

Note.—The terms Strong and Weak were first used by Jacob Grimm (1785-1863) in the terminology of verbs, and thence transferred to nouns and adjectives. By a Strong Verb, Grimm meant one that could form its preterit out of its own resources; that is, without calling in the aid of an additional syllable: Modern English run, ran; find, found; but verbs of the Weak Conjugation had to borrow, as it were, an inflectional syllable: gain, gained; help, helped.

[15.]

The stems of nouns belonging to the Consonant Declension ended, with but few exceptions, in the letter n (cf. Latin homin-em, ration-em, Greek ποιμέν-α). They are called, therefore, n-stems, the Declension itself being known as the n-Declension, or the Weak Declension. The nouns, also, are called Weak Nouns.

[16.]

If every Old English noun had preserved the original Germanic stem-characteristic (or final letter of the stem), there would be no difficulty in deciding at once whether any given noun is an a-stem, ō-stem, i-stem, u-stem, or n-stem; but these final letters had, for the most part, either been dropped, or fused with the case-endings, long before the period of historic Old English. It is only, therefore, by a rigid comparison of the Germanic languages with one another, and with the other Aryan languages, that scholars are able to reconstruct a single Germanic language, in which the original stem-characteristics may be seen far better than in any one historic branch of the Germanic group (5, Note]).

This hypothetical language, which bears the same ancestral relation to the historic Germanic dialects that Latin bears to the Romance tongues, is known simply as Germanic (Gmc.), or as Primitive Germanic. Ability to reconstruct Germanic forms is not expected of the students of this book, but the following table should be examined as illustrating the basis of distinction among the several Old English declensions (O.E. = Old English, Mn.E. = Modern English):

Gmc. staina-z,
(1) a-stemsO.E. stān,
Mn.E. stone.

I. Strong
or Vowel
Declensions

Gmc. hallō,
(2) ō-stemsO.E. heall,
Mn.E. hall.
Gmc. bōni-z,
(3) i-stemsO.E. bēn,
Mn.E. boon.
Gmc. sunu-z,
(4) u-stemsO.E. sunu,
Mn.E. son.
(1) n-stems
(Weak Declension)
Gmc. tungōn-iz,
O.E. tung-an,
Mn.E. tongue-s.

II. Consonant
Declensions

(2) Remnants
of other
Consonant
Declensions
Gmc. fōt-iz,
(a)O.E. fēt,
Mn.E. feet.
Gmc. frijōnd-iz,
(b)O.E. frīend,
Mn.E. friend-s.
Gmc. brōðr-iz,
(c)O.E. brōðor,
Mn.E. brother-s.

Note.—“It will be seen that if Old English ēage, eye, is said to be an n-stem, what is meant is this, that at some former period the kernel of the word ended in -n, while, as far as the Old English language proper is concerned, all that is implied is that the word is inflected in a certain manner.” (Jespersen, Progress in Language, § 109).

This is true of all Old English stems, whether Vowel or Consonant. The division, therefore, into a-stems, ō-stems, etc., is made in the interests of grammar as well as of philology.