Mac Eachairn

Mac Eachairn is a Scottish surname meaning "son of Eacharn". The given name Eacharn derives from the Old Irish name Echthigern, which itself carries the meaning "horse lord", composed of the elements ech "horse" and tigerna "lord". This name reflects to Celtic onomastic traditions, where equestrian imagery was often used to convey status and power.

The surname demonstrates Gaelic patronymic formation with the prefix Mac- (also found as Mc-), which indicates a clan affiliation. Its principal variant MacEachern (or McEachern) is more widely encountered, particularly in around Argyll and the Hebrides. Over time, English-influenced phonetic simplifications produced forms such as Ahearn, Ahearne, Hearn, and O'Hearn—forms that are more commonly associated with like Ó hEachthighearna families in Munster.

Today, Mac Eachairn remains a relatively rare surname principal in Scotland, featured in historical records of West Highland clans and their migrations to Nova Scotia and Ontario.

• Meaning: "Son of Eacharn" (Eacharn from Echthigern, "horse lord")
• Origin: Scottish Gaelic
• Type: Patronymic surname
• Usage regions: Scotland (esp. West Highlands), Canada