This book is designed to prepare English learners to improve one of the language subskills that is vocabulary. Basic knowledge of vocabulary is actually very essential when language learners need to use foreign language appropriately . Recognising the word function will also be unavoidable part beside enriching the amount of vocabulary. This book contains basic knowledge of vocabulary and how it works in sentences such as: suffixes, prefixes, abstract noun, compound adjectives, compoun nouns, Combining forms, Onomatopoeic words, Homonyms. Recognising words and expanding into new words by adding suffixes and prefixes in accordance to the need of its meaning and grammar is very important for language learners. This book will lead you how to develop words into your need for expressing the correct meaning and grammar. It is also important for language learners to develop the understanding of the abstract nouns which have its own form. Some others such as compound adjectives, compound nouns, combining forms are also helpful to understand and use them in the correct way. Besides, onomatopoeic words and homonyms are also useful to understand the meaning of the words and the intended meaning based on the context. The writer hopes that this book will be useful for language learners to improve the mastery of English.