Reduplicated stem (Ⅸ)
Stem Ⅸ ʔ⋅ifʕalla, yafʕallu اِفْعَلَّ، يَفْعَلُّ (the R-stem, R for “reduplication”) has an irregular shape in the citation form. In this irregular shape the theme vowel is hidden. The original shape of the stem is ʔ⋅ifʕalal–, yafʕalil– اِفْعَلَل، يَفْعَلِل .
A rarer variant is Stem Ⅺ ʔ⋅ifʕȃlla, yafʕȃllu اِفْعالَّ، يَفْعالُّ (the RL-stem), which also has an irregular shape in the citation form that hides the theme vowel.
Stems Ⅸ & Ⅺ are middle-voice stems, but in the common varieties of Arabic these stems came to be used almost exclusively for deriving verbs from adjectives of the type ʔafʕalu, faʕlȃʔu أَفْعَلُ، فَعْلاءُ , which denote colors and human physical or mental defects.
|red||he became red (intr.)|
|white||he became white (intr.)|
|one-eyed||he became one-eyed (intr.)|