In the Georgian verb system, the medial verbs are characterized by a conjugation type with mixed characteristics between conjugation Class I and Class II – hence the name medial verbs. Most medial verbs are intransitive and often describe actions of motion and nature sounds: ცხოვრობს, ცურავს, დუღს ...
Just as in other languages, some verbs share characteristics of two conjugation classes, hence the name medial verb (in German: Mittelverb, Mischtyp). Since their subject stand in nominative in the present indicative and in ergative in the aorist indicative, they belong to Conjugation Class I, even though they form the future indicative quite differently from the other Class-I verbs (or any other class) by adding ი--ებ to the verb root: წყალი დუღს - the water is boiling. წყალი იდუღებს - the water is going to boil.
Moods & Tenses
The medials share many conjugations with the standard Class-I conjugations – and are therefore often not easily distinguished from these conjugations – most notably the future indicative is constructed differently, i. e. by the ი--ებ circumfix: იცინის - she is laughing; იცინებს - she is going to laugh. There are only few exceptions to this rule, e.g. in the medial root verbs, the medials on -ობ or in the relative medial verbs (see below).
See Tschenkeli (2007:295) for details on these exceptions.
The specific conjugations of the medial verbs are explained in the pages on Conjugation Class I.
Relative Medial Verbs
Some medial verbs can express a relation to an indirect object by a certain prefix (მ-, გ-, ჰ-, ს-, გვ-, უ-, ა-, ე-). e.g. ის აზის სკამს - she is sitting on a chair; ის ეჯდება სკამს - she is going to sit on a chair. Such verbs are called relative medial verbs. Their conjugation is very similar to the normal conjugation of medial verbs but these prefixes cause some irregularities.
See Tschenkeli (1957:425, Chapter 36) for more details and examples of relative medial verbs.
Note that some grammars treat medial verbs as a separate conjugation class. More on medial verbs in Tschenkeli (1958) 28. Lektion, p. 291.