A suffix is a set of letters added to the end of a word that slightly changes its meaning, its grammatical role, or both.

Basic idea

  • A suffix comes after a base or root word, never before it.
  • Adding a suffix can create a new word or a new form of the same word (for example, plural or past tense).

What suffixes do

  • Change word form: dog → dogs, walk → walked (tense, number, etc.).
  • Change word type: strength (noun) → strengthen (verb) → strengthened (past verb form).
  • Slightly modify meaning without making it unrecognizable: pain → painful (“full of pain”), hope → hopeless (“without hope”).

Types of suffixes

  • Inflectional suffixes: change grammar only (plural, tense), like -s, -ed, -ing.
  • Derivational suffixes: create new words or word classes, like -ful, -less, -ness, -able.

Quick examples

  • teach → teacher (add -er for “person who does”).
  • power → powerful (add -ful for “full of”).
  • hope → hopeless (add -less for “without”).

TL;DR: A suffix is a letter or group of letters added to the end of a word to tweak its meaning or grammar, like -s, -ed, -ful, or -less.