A prefix is added to the front of a word, while a suffix is added to the end. Memory hook: prefix starts the same way as pre-, meaning before, and suffix ends the way it sounds, after. Un- in unkind is a prefix; -ness in kindness is a suffix.
The core difference
The difference is position: a prefix attaches before the root word, and a suffix attaches after it.
- prefix — letters added to the front of a word to change its meaning: Adding the prefix "un-" turns "kind" into "unkind".
- suffix — letters added to the end of a word to change its meaning or grammatical role: Adding the suffix "-less" turns hope into hopeless.
How to tell them apart
Both words come from Latin figere, meaning to fasten, but the piece attached to them tells you the position: prae- means before, so a prefix is fastened in front, while sub- means under or after, so a suffix is fastened on afterwards.
The same logic applies outside grammar. A phone number can carry a dialling prefix at the start, and a person's name can carry a suffix such as Jr. or PhD at the end. Some grammar terms also use both in the same word, such as unhappiness, which combines the prefix un- with the suffix -ness around the root happy.
