Hans Dieter Betz argues that μαρκαριος ("blessed"/"happy") traces its origin to Egyptian m'r, which has the same meaning.
Hans Dieter Betz, The Sermon on the Mount (Hermeneia—A Critical and Historical Commentary on the Bible; Minneapolis: Fortress Press, 1995), 92-93
Philological investigations have shown that the adjective μαρκαριος is derived from an older word μακαρ, and that its roots may not be Greek. Some scholars have proposed and Egyptian origin, pointing to Egyptian m’r as having the same meaning as μαρκαρ(ιος). Beatitudes are rather frequent in Egyptian literature, so that an Egyptian origin is conceivable. This hypothesis has gained in credence through Jan Assman’s observation of the two-line beatitudes, win which the second line gives a reason.