What is the definition of a word family?

Word families are groups of words that have a common pattern or feature. They may have either a similar sound or they have the same letter combinations. For example, one basic word family are “at” sounding words: bat, cat, fat, hat, mat, pat, rat, sat, tat, and vat. There are 37 common word families in the English language, according to Wylie and Durrell who identified these words in 1970. Many nursery rhymes contain word families. Teaching word families is a strategy to help kids read many words with ease and to develop rhyming skills to expand their reading sight vocabulary.