Diminutive of Mercedes, from Spanish meaning mercies or graces.
Merdie is a diminutive of Mercedes, from Spanish meaning "mercies" or "graces." That gives it a gentle devotional background, softened further by the affectionate nickname form.
It feels domestic, warm, and tied to the long tradition of virtue names that became pet forms over time. Merdie has an old-fashioned charm that makes it feel both simple and endearing. Its rarity today gives it a vintage quality, as though it belongs to an earlier generation of intimate, family-used names. The effect is modest and affectionate rather than grand.