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ab- Prefix indicating "off" or "away"
Not a productive prefix in Spanish, and it appears only as a relic in verbs like abrir. From Latin ab 'id.' From Proto-Italic *ap- 'id.' From Proto-Indo-European *h2epo 'id.' As an allative preposition, the word had a full grade *h2epo (preserved in the prefix ab- above) and a zero grade *h2po (preserved in the prefix po-).
Indo-European
Italic
Umbrian ap-, Paelignian af-, Oscan af-
Germanic
Gothic af, aff-, Old Norse af, Old High German aba, Old Saxon af, English of
Albanian
Albanian pa "without"
Balto-Slavic
Lithuanian po-, Latvian ap "beneath," Old Church Slavonic po, Russian po
Hellenic
Ancient Greek ἀπό (apó) "far from"
Messapian
Messapian apa "from"
Indo-Iranian
Sanskrit ápa "away," Avestan apa-