I. INTRODUCTION

According to Manser (1995: 461), Vocabulary is the total number of words in a language. While Morales (2004-2005) stated that vocabulary is a listing of the words used in some enterprise. Furthermore, Ur in Hidayati (2007: 7) stated that vocabularies are the words that are taught in the foreign language. From the opinions above, we can conclude that vocabulary is a listing of all words that are taught in the foreign language. Vocabulary refers to the words we must understand to communicate effectively.

Many compelling reasons for providing students with instruction to build vocabulary, none is more important than the contribution of vocabulary knowledge to reading comprehension. Indeed, one of the most enduring findings in reading research is the extent to which students’ vocabulary knowledge relates to their reading comprehension. Most recently, the National Reading Panel (2000) concluded that comprehension development cannot be understood without a critical examination of the role played by vocabulary knowledge. Given that students’ success in school and beyond depends in great measure upon their ability to read with comprehension, there is urgency to providing instruction that equips students with the skills and strategies necessary for lifelong vocabulary development.

One of the most persistent findings in reading research is that the extent of students’ vocabulary knowledge relates strongly to their reading comprehension and overall academic success. This relationship seems logical; to get meaning from what they read, students need both a great many words in their vocabularies and the ability to use various strategies to establish the meanings of new words when they encounter them. Young students who don’t have large vocabularies or effective word-learning strategies often struggle to achieve comprehension. Their bad experiences with reading set in motion a cycle of frustration and failure that continues throughout their schooling. Because these students don’t have sufficient word knowledge to understand what they read, they typically avoid reading. Because they don’t read very much, they don’t have the opportunity to see and learn very many new words. This sets in motion the well known “Matthew Effects,” Stanovich’s (1986) application of Matthew, 25:29–“the rich get richer and the poor get poorer.” In terms of vocabulary development, good readers read more, become better readers, and learn more words; poor readers read less, become poorer readers, and learn fewer words.

This particular relationship between vocabulary knowledge and reading comprehension seems clear. But vocabulary knowledge contributes to reading success in other important ways that are perhaps less obvious. For beginning readers, evidence indicates a link between word knowledge and phonological awareness. Young children who have a large number of words in their oral vocabularies may more easily analyze the representation of the individual sounds of those words. In addition, vocabulary knowledge helps beginning readers decode, or map spoken sounds to words in print. If children have the printed words in their oral vocabulary, they can more easily and quickly sound out, read, and understand them, as well as comprehend what they are reading. If the words are not in children’s oral vocabulary, they have trouble reading the words and their comprehension is hindered (National Reading Panel, 2000). Thus, an extensive vocabulary is the bridge between the word-level processes of phonics and the cognitive processes of comprehension. The issue to address next, then, is just how many words do students need to know so as to read with comprehension. This is exactly what constitutes an “extensive” vocabulary.

II. Body

Vocabulary is the basic that must be learnt first by learners. It will help the learner in learning English language well. As Harmand and Stork (1976:250) stated that vocabulary is a stock of words which are at the disposal of speaker or writer. As in Brainy Media.com that vocabulary is a list or collection of words arranged in alphabetical order and explained ; a dictionary or lexicon either of whole language, a single work or author, a branch of science or wordbook. Besides, Hindmarsh R (1980) stated that vocabulary is a core component of language proficiency and provides much of basis for how well learners speak, listen, read and write.
Vocabulary refers to the words we must understand to communicate effectively. Educators often consider four types of vocabulary there are :

1.      Reading vocabulary
A person’s reading vocabulary is all the words he or she can recognize when reading. This is the largest type of vocabulary simply because it includes the other there.

2.      Listening vocabulary
A person’s listening vocabulary is all the words he or she can recognize when listening to speech. This vocabulary is aided in size by context and tone of voice.

3.      Writing vocabulary
A person’s writing vocabulary is all the words he or she can employ in writing. Contrary to the previous two vocabulary types, the writing vocabulary is stimulated by its user.

4.      Speaking vocabulary
A person’s speaking vocabulary is all the words he or she can use in speech. Due to the spontaneous nature of the speaking vocabulary, words are often misuse – though slight and unintentional, may be compensated by facial expressions, tone of voice, or hand gestures.
Vocabulary plays a fundamental role in the riding process, and contributes greatly to a reader’s comprehension. A reader cannot understand a text whitout knowing what most of the words mean. Students learn the meaning of most words indirectly, through everyday experiences with oral and written language. Other words are learned through carefully designed instruction.

a). Vocabulary growth

Initially, in the infancy phase, vocabulary growth requires no effort. Infants hear words and mimic them, eventually associating them with objects and actions. This is the listening vocabulary. The speaking vocabulary follows, as a child's thoughts become more reliant on its ability to express itself without gestures and mere sounds. Once the reading and writing vocabularies are attained – through questions and education – the anomalies and irregularities of language can be discovered.

In first grade, an advantaged student (i.e. a literate student) knows about twice as many words as a disadvantaged student. Generally, this gap does not tighten. This translates into a wide range of vocabulary size by age five or six, at which time an English-speaking child will know about 2,500–5,000 words. An average student learns some 3,000 words per year, or approximately eight words per day. After leaving school, vocabulary growth reaches a plateau. People may then expand their vocabularies by engaging in activities such as reading, playing word games, and participating in vocabulary programs.

III. Conclusion

Vocabulary Learning is an important aspect in learning a foreign language.  Students will improve a lot if they learn more words and expressions.  As linguist David Wilkins (in Thornbury 2002: 13) says that learning vocabulary is very important.  ‘Without grammar, very little can be conveyed, without vocabulary nothing can be conveyed.  'Thus, vocabulary is the flesh of a language while grammar is a framework.  In order to use language productively, students must know a certain amount of vocabulary, not only to communicate verbally, but also in writing.  This is in line with the concept of a communicative approach where students have a great opportunity to use language directly in class activities.  This approach is useful in increasing student vocabulary.  Through this approach students are forced to use language directly both in oral and written communication.

Reference:
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