1 Phonology is the study of the sound system of a language or languages. 2  Morphology is a branch of biology which concerns the form and structure or organisms; this definition includes the form and structure of words within a language, and their modification. Syntax is the branch of linguistics that covers the grammatical arrangements of words within sentences, and how we use speech in communication. 2  Semantics deals with the study of meaning; how we combine words to create meaningful discourse. 3  It studies the relationship between signs and symbols and what they represent.