Suffix and Prefix Defined

Prefix 
A prefix is a group of letters placed before the root of a word. For example, the word "unhappy" consists of the prefix "un-" [which means "not"] combined with the root (stem) word "happy"; the word "unhappy" means "not happy."
Suffix 
A suffix is a group of letters placed after the root of a word. For example, the word flavorless consists of the root word "flavor" combined with the suffix "-less" [which means "without"]; the word "flavorless" means "having no flavor."

A Short List of Prefixes:

PREFIX	MEANING	EXAMPLES
de-	from, down, away reverse, opposite	decode, decrease
dis-	not, opposite, reverse, away	disagree, disappear
ex-	out of, away from, lacking, former	exhale, explosion
il-	not	illegal, illogical
im-	not, without	impossible, improper
in-	not, without	inaction, invisible
mis-	bad, wrong	mislead, misplace
non-	not	nonfiction, nonsense
pre-	before	prefix, prehistory
pro-	for, forward, before	proactive, profess, program
re-	again, back	react, reappear
un-	against, not, opposite	undo, unequal, unusual

A Short List of Suffixes:

SUFFIX	MEANING	EXAMPLES
-able	able to, having the quality of	comfortable, portable
-al	relating to	annual, comical
-er	comparative	bigger, stronger
-est	superlative	strongest, tiniest
-ful	full of	beautiful, grateful
-ible	forming an adjective	reversible, terrible
-ily	forming an adverb	eerily, happily, lazily
-ing	denoting an action, a material, or a gerund	acting, showing
-less	without, not affected by	friendless, tireless
-ly	forming an adjective	clearly, hourly
-ness	denoting a state or condition	kindness, wilderness
-y	full of, denoting a condition, or a diminutive	glory, messy, victory,