Germanic languages
Morphology

The oldest Germanic languages have the typical complex inflected morphology of old Indo-European languages, with four or five noun cases; verbs marked for person, number, tense and mood; multiple noun and verb classes; few or no articles; and rather free word order. The old Germanic languages are famous for having only two tenses (present and past), with three PIE past-tense aspects (imperfect, aorist, and perfect/stative) merged into one and no new tenses (future, pluperfect, etc.) developing. There were three moods: indicative, subjunctive (developed from the PIE optative mood) and imperative. Gothic verbs had a number of archaic features inherited from PIE that were lost in the other Germanic languages with few traces, including dual endings, an inflected passive voice (derived from the PIE mediopassive voice), and a class of verbs with reduplication in the past tense (derived from the PIE perfect). The complex tense system of modern English (e.g. In three months, the house will still be being built or If you had not acted so stupidly, we would never have been caught) is almost entirely due to subsequent developments (although paralleled in many of the other Germanic languages).

Among the primary innovations in Proto-Germanic are the preterite present verbs, a special set of verbs whose present tense looks like the past tense of other verbs and which is the origin of most modal verbs in English; a past-tense ending; (in the so-called "weak verbs", marked with -ed in English) that appears variously as /d/ or /t/, often assumed to be derived from the verb "to do"; and two separate sets of adjective endings, originally corresponding to a distinction between indefinite semantics ("a man", with a combination of PIE adjective and pronoun endings) and definite semantics ("the man", with endings derived from PIE n -stem nouns).

Note that most modern Germanic languages have lost most of the inherited inflectional morphology as a result of the steady attrition of unstressed endings triggered by the strong initial stress. (Contrast, for example, the Balto-Slavic languages, which have largely kept the Indo-European pitch accent and consequently preserved much of the inherited morphology.) Icelandic and to a lesser extent modern German best preserve the Proto–Germanic inflectional system, with four noun cases, three genders, and well-marked verbs. English and Afrikaans are at the other extreme, with almost no remaining inflectional morphology.

The following shows a typical masculine a -stem noun, Proto-Germanic *fiskaz ("fish"), and its development in the various old literary languages:
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