Otdfbt

Do the Ukrainian have any verbs, whose past tense forms base on the lexical root, that differs from the lexical root of the infinitive form (by analogy with the Latin verb fero > tuli)?

As I can see, the verb ferō changes lexical root not just when it has just past tense but exactly when perfect past tense, because imperfect is also past tense.

Ukrainian like others Slavic languages (for example Polish, Russian) has almost total similar system but with one different: verb can have only one mode which is imperfect or perfect, and all of them have infinitive form.

And here Ukrainian like others Slavic languages has many ways to change imperfect verbs to perfect via:

• add or remove prefix: світити – засвітити, вабити – привабити;


• add, remove or change suffix: повторювати – повторити, допомагати – допомогти;


• alternating sounds at the root: збирати – зібрати
  


• change of emphasis: розки́дати – розкидáти, скли́кати – скликáти;


• and finally our theme, change of roots: брати – взяти, ловити – упіймати, заходити – зайти.

And of course, count of these verbs is big enough.

By the way, a changing of root but with saving main meaning is suppletion.

Ukrainian language has plenty of irregular verbs of this kind. In most cases, the inconsistency has been caused by two distinct roots existing in old language, and one variant retained for infinitive/present/imperfective, and another used for past/perfective.

Although quite often, these two forms somewhat overlap (as shown in stegetsj's excellent answer), several words have very clear disctinction between the infinitive and past forms. Two most prominent examples that come to my mind are:

• 
  є → був (cf. Old Slavonic єсті/биті);


• 
  йти → йшов.