ABSTRACT
§ 53. In Old English this term is used chiefly for the variation of vowel seen in the stems of strong verbs, which may be called “graded” verbs, as for instance in rīdan, to ride, beside its preterite rād and its past participle riden. The vowels thus varied occur in regular series; for example, ī can interchange with ā or with ĭ, but not with ō or u.
