[医] 分开, 分离; 切开

[ noun ]
a diacritical mark (two dots) placed over a vowel in German to indicate a change in sound
<noun.communication>

Diaeresis \Di*[ae]r"e*sis\, Dieresis \Di*er"e*sis\ (?; 277), n.;
pl. {Di[ae]reses} or {Diereses}. [L. diaeresis, Gr. ?, fr. ?
to divide; dia` through, asunder + ? to take. See {Heresy}.]
1. (Gram.) The separation or resolution of one syllable into
two; -- the opposite of syn[ae]resis.

2. A mark consisting of two dots [[umlaut]], placed over the
second of two adjacent vowels, to denote that they are to
be pronounced as distinct letters; as, co["o]perate,
a["e]rial.