a prefix occurring in loanwords from Greek ( diabetes; dialect ) and used, in the formation of compound words, to mean "passing through" ( diathermy ), "thoroughly," "completely" ( diagnosis ), "going apart" ( dialysis ), and "opposed in moment" ( diamagnetism ).
Also, esp. before a vowel, di- .
[ diá (prep.) through, between, across, by, of, akin to dýo TWO and di- DI- 1 ]