Examples: cartography card archaeology archetype monarchy legal loyal purse personal cinema kinase car carpenter hippopotamus Mesopotamia dative data date
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Old Irish ar-
← Proto-Celtic *ɸare- (inherited)
← Old Irish ar (mention)

→ Irish athraigh (mention)
→ Irish aithrí (mention)
→ Scottish Gaelic atharraich (mention)
→ Manx arree (mention)
→ Old Irish arcessi (affix)
→ Old Irish arachrin (affix)
→ Old Irish argaib (affix)
→ Old Irish aricc (affix)
→ Old Irish armidethar (affix)
→ Old Irish arnaisc (affix)
→ Old Irish doairbir (affix)
→ Old Irish doáirci (affix)
→ Old Irish doairicc (affix)
→ Old Irish arbeir (affix)
→ Old Irish adeirrig (affix)
→ Old Irish arreith (affix)
→ Old Irish irlam (affix)
→ Old Irish arsissedar (affix)
→ Old Irish arpeti (affix)
→ Old Irish arfen (affix)
→ Old Irish doaurchain (affix)
→ Old Irish doairngir (affix)
→ Old Irish doaurling (affix)
→ Old Irish arléici (affix)
→ Old Irish conerchloí (affix)
→ Old Irish indárban (affix)
→ Old Irish comthururas (affix)
→ Old Irish aráili (affix)
→ Old Irish arcela (affix)
→ Old Irish arcoat (affix)
→ Old Irish arcuilli (affix)
→ Old Irish arbiatha (affix)
→ Old Irish arcain (affix)
→ Old Irish arcondla (affix)
→ Old Irish ardíbdai (affix)
→ Old Irish arneat (affix)
→ Old Irish airnaide (affix)
→ Old Irish airnigde (affix)
→ Old Irish artróetha (affix)