What is the term for a word from which other words can be derived?

The term for a word from which other words can be derived is indeed the base word. A base word serves as the foundational element upon which additional words can be formed by adding prefixes, suffixes, or other modifications. For example, the base word "happy" can lead to the derivations “happiness,” “unhappy,” and “happily.”

Understanding base words is fundamental to exploring word families and the structure of the English language. The other terms present in the options serve different purposes. An affix refers to a prefix or suffix that is added to a base word to alter its meaning or grammatical function. A blend refers to a word that is created by merging parts of two different words (like “smog” from “smoke” and “fog”). The alphabetic principle describes the understanding that letters and letter patterns represent the sounds of spoken language, which is a different concept altogether.

Recognizing the role of base words is crucial in effective reading instruction, as it enhances vocabulary development and comprehension skills for students.