As the previous posters have said, PhD means more-or-less “Philosophy Doctor”. MD means “Medical Doctor”, “JD” “Jurisprudence (legal) Doctor”, while “DEd” swaps the order for “Doctor of Education”.
On a lighter note, most of the folk I know with such degrees recognize “BS” as meaning “Bull Sh*t”, “MS” as “More of the Same”, and “PHD” as “Piled Higher and Deeper”.

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