Vocabulary is described with the following three tiers:

Basic Vocabulary

The basic words form the first tier of vocabulary. These words normally have a single meaning and do not require instruction. Early reading words, sight words, adjectives, verbs, nouns, etc., are portrayed in this tier. 8000-word families in English comprise this tier.

High-frequency Vocabulary

Also called the multiple meaning vocabulary tier, this tier comprises words used in a variety of domains, adult communication, literature, etc. It influences reading and speaking. 7000-word families comprise this tier. The characteristics for tier two words are as follows:

• It has multiple meanings
• Vital for reading comprehension
• Typical mature language
• Descriptive vocabulary
• A diverse environment use these words
• Used for direct instruction

Low-frequency vocabulary

The words that are used only when specifically required or in a particular domain like weather, technology, geographical region, occupation, hobbies, school, etc. comprise this tier. About four lakh words in vocabulary in English comprise this tier.