Prefixes: des- undoes, re- repeats

A prefix clips onto the front of a word and bends its meaning in a fixed direction. Learn the piece once and a family of words opens up:

• deshacer - to undo (from hacer, to do)
• imposible - impossible (from posible)

Spanish prefixes at a glance

The four that do most of the work. Look at the coloured piece, then the base it sits on.

The rest (anti-, sub-, super-, ex- and friends) are in the long tail further down. They are for recognising, not drilling.

des-: undo, reverse, opposite

Des- works like English un- or dis-. On a verb it undoes the action; on a noun or an adjective it gives the opposite.

In a sentence:

• Deshice la maleta. - I unpacked the suitcase.
• El gato desapareció. - The cat disappeared.

When you meet a new des- word, strip the des- off: the root underneath is usually a word you know. Breakfast is the famous one: desayunar is to break the fast, from ayunar, to fast.

re-: again, back

On a verb, re- means again or back, as in English.

• Van a reconstruir el puente. - They are going to rebuild the bridge.

In everyday speech, Spanish often says again with volver a plus an infinitive instead:

• Vuelvo a leer el libro. - I'm reading the book again.

Two cautions. Many old re- words are not built from anything you can strip off: recordar is to remember and recoger is to pick up. And in casual speech, above all in Argentina and Uruguay, re- also works as "really", with no repetition at all, often written as a separate word:

• Es re lindo. - It's really lovely. (Argentina, casual)
• Lo hiciste requetebién. - You did it really, really well. (casual, everywhere)

On a verb, read re- as again; on a casual adjective, read it as very.