Historical linguistics (also called diachronic linguistics) is the study of language change. It has five main concerns:
English prefixes are affixes (i.e., bound morphemes that provide lexical meaning) that are added before either simple roots or complex bases (or operands) consisting of (a) a root and other affixes, (b) multiple roots, or (c) multiple roots and other affixes. Examples of these follow:
English words may consist of multiple prefixes: anti-pseudo-classicism (containing both an anti- prefix and a pseudo- prefix).
There are several prefixes in the Hebrew language which are appended to regular words to introduce a new meaning. In Hebrew, the letters which form these prefixes are called "formative letters" (Hebrew: אוֹתִיּוֹת הַשִּׁמּוּשׁ, Otiyot HaShimush). Eleven of the twenty-two letters of the Hebrew alphabet are considered Otiyot HaShimush. These letters are Aleph (א), Bet (ב), He (ה), Vav (ו), Yud (י), Kaf (כ), Lamed (ל), Mem (מ), Nun (נ), Shin (ש), and Tav (ת). A mnemonic to remember these letters is "Eitan, Moshe, v'Kalev" (Hebrew: אית"ן מש"ה וכל"ב) which translates to "Eitan, Moshe, and Caleb."