sean-

Etymology
From.

Prefix

 * 1) old, aged; senior; mature; long-established, old-fashioned;  old style
 * 2)  great, exceeding; over-

Usage notes

 * Triggers lenition (except of d, s and t):
 * sean- + máthair → seanmháthair ("grandmother"; lit. 'old mother')
 * sean- + deasc → seandeasc ("old desk")