What is a syllable or word element that can only occur in front of after root stem?

The syllable or word element that can only occur in front of or after a root stem is called an affix.

There are two main types of affixes:

* Prefixes: These are affixes that come before the root word. Examples include "un-", "re-", "pre-", "dis-", and "mis-".

* Suffixes: These are affixes that come after the root word. Examples include "-ing", "-ed", "-er", "-ly", and "-ness".

Affixes can change the meaning, grammatical function, or part of speech of a word.

For example:

* happy (root word)

* unhappy (prefix "un-" added, meaning the opposite of happy)

* happiness (suffix "-ness" added, changing the word from an adjective to a noun)

Let me know if you would like to explore prefixes or suffixes in more detail!