'Dia-' definitions:
-
Dia- \Di"a-\, Di- \Di-\ . [Gr. dia` through; orig., dividing
into two parts; akin to ? two. See Two, and cf. 1st Di-.]
A prefix denoting through; also, between, apart, asunder,
across. Before a vowel dia- becomes di-; as, diactinic;
dielectric, etc.
[1913 Webster]
