Prefix · self / automatic
Signals self-action or automaticity: automatic, autobiography, autopilot, autograph.
Written by Bryan López, English teacher · Updated
Auto- comes from Greek "autos" (self, by itself) and signals that something acts by itself or without external intervention: automatic = works by itself; autobiography = a book written by the subject about their own life; autocorrect = correction the system applies by itself; autonomous = governs itself.
Auto- is one of the most productive prefixes in modern technology: autopilot, autofocus, autosave, autocomplete. It also appears in everyday words: autograph (a signature made by the person's own hand), autoimmune (a response from the body's own immune system). Recognising auto- instantly unlocks dozens of tech and everyday words.
Attaches to nouns and adjectives with no spelling change. Modern English usually writes it without a hyphen:
Auto- is identical in Spanish and English. Pronunciation: /ˈɔːtəʊ/, with the "au" long as in "thought." In informal use, "auto" alone means "car" in some varieties of English and in several other languages.
auto-/ˈɔːtəʊ/
Tap the button to hear how the prefix sounds. Each word in the table has its own audio.
"Autobiography" = auto (self) + bio (life) + graphy (writing) = the person writes about their own life. "Biography" = someone else writes about the subject's life. The prefix auto- marks who the author is.
"Autonomous" = capable of making its own decisions (a self-driving car is autonomous). "Automatic" = operates by itself without requiring human action each time (an automatic door, an automatic gearbox). A car can be automatic (no manual gearshift) without being fully autonomous (without being able to drive itself).
A trick to remember it
Auto- = "self": automatic = works on its own, autobiography = you write your own life story, autopilot = the system flies on its own. It is one of the easiest prefixes to recognise because it is identical in Spanish and English in almost every word.
Exercise 1 · Form the word
Exercise 2 · Pick the right one
"The car has an ___ braking system that stops the vehicle before the driver can even react."
Exercise 3 · Pick the right one
What is the difference between "autobiography" and "biography"?
The prefix auto- signals self-action or automaticity: automatic, autobiography, autopilot, autograph. In Spanish it usually maps to auto-.
The prefix auto- is pronounced /ˈɔːtəʊ/. For example, "automatic".
"matic" becomes "automatic". It is a typical example of the auto- prefix.
un-, re-, pre-, dis-, over-, in-... every beginning you need to unlock thousands of English words at once.