A word. Many groups of letters is called a sentence(:
Alpha and beta are the first two letters of the Greek one...
i think the group of notes is a segment! :)
A group of dancers are called a troupe
No, I don't know where you got that idea, but a group of flamingos is called a flock.
The legal status for a group of companies is that it is called a corporate group.
A group of postal letters is called a mail or a batch of mail.
a small group (5 letters)
prefix
prefix
A group of trees is called a wood from which a forest area could be called a woodland.
Company, ensemble.
set
Acronym
it is called simply a group of kings and queens!!
Your're looking for the word suffix.
A sentence or group of letters which helps you remember information because of the initial letters is called a mnemonic device. (It's named for a Greek muse.) An example would be Roy G Biv (colors of the spectrum: red, orange, yellow, green, blue, indigo violet.)
Aside from Kanji, there is Hiragana and Katakana (which are under a group called Kana). When Japanese is written using English letters (technically Latin letters), it's called "romaji" or romanization.