Předpony a významy sloves

You already know that a prefix can make a verb perfective: psát → napsat. But most prefixes do more than that: they add a new meaning, rather like English particles in write down, write out, write off. The new verb is perfective, and it builds its own imperfective partner with a suffix.

One root, a family of verbs

Perfective	Meaning	Imperfective partner
napsat	write (complete)	psát
dopsat	finish writing	dopisovat
přepsat	rewrite, copy out again	přepisovat
podepsat	sign ("write under")	podepisovat
zapsat	write down; enrol	zapisovat
opsat	copy from someone (at school: cheat)	opisovat
popsat	describe	popisovat
vypsat	write out; announce (a competition, a tender)	vypisovat

Only na- is "empty" here; it adds completion and nothing else, so napsat pairs with plain psát. Every other prefix creates a new verb with a new partner. A learner who forms *přepsávám has guessed the suffix; the real form is přepisuju (more formally přepisuji).

The same prefixes on other verbs

The meanings repeat across roots, which is why prefixes are worth learning as a system. In a Czech pub you can hear most of them with pít:

• Dopij to, jdeme. - Finish your drink, we're leaving. (do-: to the end)
• Vypil celý půllitr naráz. - He downed the whole half-litre in one. (vy-: completely, out)
• Napij se vody. - Have a sip of water. (na- se: a little, enough)
• Připijme si na zdraví! - Let's drink a toast! (při-: adding to)
• Na svatbě se opil. - He got drunk at the wedding. (o- se: affecting the whole person)

And with other verbs: dodělat (finish doing), předělat (redo), doplatit (pay the rest), přeplatit (overpay), přespat (stay overnight).

What to watch

Do not treat all prefixed forms as the same verb. Přepsala diplomku (she rewrote her thesis) and Dopsala diplomku (she finished writing it) describe two different stages of a student's June. When you meet a new prefixed verb, learn it with its imperfective partner, exactly as you would learn a new word.