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-al (2), -ar Adjective-forming suffix.

From Latin -alis 'id.' and -aris 'id.' respectively. From Proto-Italic *-li- 'id.' and *-ri- 'id.' From Proto-Indo-European *-li̯- 'id.'

In Proto-Italic, the original suffix was *-li- but changed to *-ri- in *keli-ri-s "fast" due to dissimilation (see célere).