A diacritic consisting of two dots ( ¨ ) placed over a letter, used among other things to indicate umlaut or diaeresis.(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "trema" in a sentence
"I always need something like a "smaller than" symbol or a "trema" symbol (double dot), so I alternate."
"For example, when you are in babel's dutch language mode you can write twee "en in which" is a trema, which is not equivalent to twee\ "en, which is then (actually always) specifically an umlaut."
"Probably because of that strange little trema (a French kind of umlaut or diaeresis) over the "e"."