Lexicology

Lexicology is the part of linguistics or a branch of linguistics concerned with the meaning and application of words. Dealing with lexicology, there are some technical terms we have to comprehend, such as :

1. Lexicon : The collection of word (the internalized dictionary), that every speaker of the language has.
2. Lexeme : The fundamental unit of the lexicon of the language.
3. Lexicography : The process of writing, editing, and/or compiling a dictionary
4. Lexicographer : The author and editor of a dictionary

According to the difinition of lexicology, automatically we talk about word. There are some examples of how lexemes deal with the word :

1. The word eat, eats, eating, ate, and eaten are forms of the lexeme EAT
2. The word drink, drinks, drinking, drank, and drunk are forms of the lexeme DRINK

in linguistic the lexeme is always written in CAPITAL LETTERS

Sources :

http://www.merriam-webster.com/dictionary/lexicology
http://www.slideshare.net/Andriyanieka12/8-lexicology-word-word-classes-18509390