It is often asserted that the Germanic languages have a highly reduced system of inflections as compared with Greek, Latin, or Sanskrit.
As an example, there are fewer than 500 years between the Gothic Gospels of 360 CE (see Ulfilas) and the Old High German Tatian of 830 CE, yet Old High German, despite being the most archaic of the West Germanic languages, is missing a large number of archaic features present in Gothic, including dual and passive markings on verbs, reduplication in Class VII strong verb past tenses, the vocative case, and second-position (Wackernagel's Law) clitics.
The older distinction between athematic and thematic stems had been lost, and generally nouns were divided into several declension classes based on the vowels or consonants before the case endings.
The neuter nouns of all classes differed from the masculines and feminines in their nominative and accusative endings, which were alike.
The dative singular of ablauting an-stems would also be affected by Verner's law itself, causing the voicing of an originally voiceless root-final consonant.
[9] Kroonen reconstructs the following masculine an-stems incorporating Kluge's Law (of which he is an ardent supporter) and usually assuming the amphikinetic accent pattern.
[9] One zero-grade–ablauting an-stem in particular, *hrīmô ("hoarfrost"), would thus gain a uniquely irregular declension of its own, due to a combination of Kluge's law alternations, post–heavy-syllable geminate shortening, and the loss of an original root-final f in several forms, such as the nominative singular.
The r-stems were limited only to a group of five close kinship terms: *fadēr ‘father’, *mōdēr ‘mother’, *brōþēr ‘brother’, *swestēr ‘sister’ and *duhtēr ‘daughter’.
Adjectives, determiners and pronouns agreed with the noun they qualified in case, number, and gender, although without a separate vocative form.
Globally, a distinction can be made between a/ō-stems (the vast majority), ja/jō-, i-, and u-stems (which were declined almost identically) and n-stem or "weak" adjectives.
A unique feature of Germanic adjectives was the distinction between strong and weak declensions, originally with indefinite and definite meaning, respectively.
This traditional account of the development and functioning of the dual adjective inflection system is largely assumption based.
[16] This, in turn, suggests that the traditional account of the development of the Germanic strong vs. weak system of adjective inflection may be incorrect.
Comparatives and ordinals used an alternative variety of the weak inflection, in which the feminine forms were not those of the ōn-stem nouns but of the īn-stems.
The Old Norse formation of the masculine and feminine singular pronouns is not fully understood, but appears to go back to a form *hanaz.
Unique within Germanic was that the pronouns of the first and second person retained distinct dual forms, which referred specifically to two individuals.
Note that, although Old Norse has an inflected mediopassive, it is not inherited from Proto-Germanic, but is an innovation formed by attaching the reflexive pronoun to the active voice.
Verbs in Proto-Germanic were divided into two main groups, called "strong" and "weak", according to the way the past tense is formed.
[26] Strong verbs were divided into seven main classes, distinguished by the ablaut pattern, which in turn was usually determined by the shape of the root.
[27] The initial s- of the original stem apparently underwent Verner's law alternation when the reduplicating prefix was added, and became -z- (as in Gothic saizlēp for the past tense of slēpan, and the four Icelandic ri-verbs).
[28] Verner's law alternations (f-b, þ-d, h-g, hw-gw, s-z) generally occurred in the final stem consonant of all strong verbs.
[29] The alternations were somewhat more complicated in verbs containing labiovelars (hw, kw or gw), since these underwent further changes in Germanic.
This applied both to stem-initial and stem-final labiovelars, and could be seen in verbs such as *strīkwaną "to stroke", where the -u- of the ending in the past nonsingular indicative (but not subjunctive) triggered delabialisation.
The 2nd person singular past indicative ending -t generally triggered assimilation of the preceding consonant according to the Germanic spirant law:[32] Strong verbs had four principal parts, from which the remaining forms could be derived.
The past third-person singular indicative is used to demonstrate the second principal part, and the second-person form with its ending -t is shown as well.
This suffix is now generally held to be a reflex of the reduplicated past imperfect of PIE *dʰeh1- originally "put", in Germanic "do".
Already a small relic class in Proto-Germanic, at most three verbs are reconstructible: *bringaną "to bring", *brūkaną "to need", *būaną "to dwell".
Their past tense replaced the initial -d- with -t-, with the preceding consonant assimilating to the suffix according to the Germanic spirant law: Class 2 consisted of verbs ending in -ôną.
It also remained optional for a long time, with verbs still occasionally appearing in other positions for poetic reasons in Middle Dutch.
However, since some verb endings had already fallen together, especially in the strong past singular and in the passive voice, the use of personal pronouns must have already been common, but it was likely still optional.