Knowing a word means knowing both its sound and its meaning, while being able to use a word requires four kinds of information:
1) its sounds
2) its meanings
3) how related words such as the plural (for nouns) and past tense (for verbs) are formed
4) its category and how to use it in a sentence
lexicon - a list of words on a particular subject or in a language in alphabeical order
dictionary - a book that gives a list of the words of a language in alphabetical order and explians what they mean or gives a word for them in a foreign language【相当于lexicon + 每个单词的释义】
vocabulary - a list of words with their meanings, especially in a book for learning a foreign language【相当于dictionary的mini版本，且不要求单词顺序】
Syntax(句法) is the grammar, structure, or order of the elements in a language statement. Semantics(语义) is the meaning of these elements.
The study of the rules that govern the formation of words and internal structure of words is called morphology(形态学).A morpheme(词素) is the smallest meaning-bearing unit of a language. It is an arbitrary union of sound and meaning that cannot be further divided.Derivational morphemes, including free morphemes, prefixes and suffixes, produce new words from existing words
Inflectional morpheme is another type of morphemes that changes the form of a word but does not change the central meaning of the word, nor its lexical category. They are always attached to the ends of words to conform to different roles in a sentence or in discourse.
prefix: the beginnings of the words; suffix: the ends of the words.