1 historical linguistics: Historical linguistics is the subfield of linguistics that studies language change.

2 apocope: Another well-documented sound loss is the deletion of a word-final vowel segement, a phenomenon called apocope.

3 epenthesis: A change that involves the insertion of a consonant or vowel sound to the middle of a word is known as epenthesis.

4 metathesis: Sound change as a result of sound movement is known as metathesis.

5 compounding: Compounding is a process of combining two or more words into one lexical unit.

6 derivation: Derivation refers to the process by which new words are formed by the addition of affixes to the roots.

7 blending: Blending is a process of forming a new word by combining parts of other words.

8 back-formation: Back-formation is a process by which new words are formed by taking away the suffix of an existing word.

9 semantic broadening: Semantic broadening refers to the process in which the meaning of a word becomes general or inclusive than its historically earlier denotation.

10 semantic narrowing: Semantic narrowing is a process in which the meaning of a word becomes less general or inclusive than its historically earlier meaning.

11 semantic shift: Semantic shift is a process of semantic change in which a word loses its former meaning and acquire a new, sometimes related, meaning.

12 protolanguage: It refers to a family of a language.

A protolanguage is the original form of a language family that has ceased to exist.The proto form can be reconstructed by identifying and comparing similar linguistic forms with similar meanings across related languages.

13 sound shift: It refers to the systematic modification of a series of phonemes.