In my experience, students who are learning English always want to know more words because they always feel they do not know enough. While the pursuit of words is admirable and important, it is also important to remember when learning words to learn words in context. Many words have different meanings. They also have various forms (word families) and collocate with other words. So while I give you lists of essential English vocabulary please, please learn the words in CONTEXT (and the various forms of the word).
Essential English Vocabulary Lists
The following sites will give you word lists of varying lengths for General, Academic and Business English. Some include pronunciation and definitions of words.
The Oxford 3000
The keywords of the Oxford 3000 were carefully selected by language experts and experienced teachers as the words which should receive priority in vocabulary study. The site gives the word in written form and then you can also choose from two settings where you can hear the word pronounced with British or an American accent.
Oxford Advanced Learner’s Dictionary- The Academic Word List
DOLCH BASIC WORD LIST
This site give you a list of 200+/- of the most common words that children read.
English Club- Business English Vocabulary
These pages list some of the most common words and phrases in thirteen different business areas, together with financial terms in British and American English.