what is a copula?

(Unless one changes the predicate into a prepositional object: "tá mé i mo dhochtúir" = "I am in my doctorhood = I am a doctor." see classificatory and identificatory clauses without the copula or bí and is further below.

Instead of that there is an seperate copula (in the simple form is), that does not count as a real verb, although it is related to the German "ist" or English "is" and is also so translated. It is seen more as a particle, in the best case as a defect verb.

uses of the copula

The use of the copula is limited in Irish to the following, specific, yet frequently occurring uses:

• coupling of the predicate noun and the subject in classificatory and identificatory clauses
  e.g.: Is dochtúir é. = He is a doctor. Is é an dochtúir é. = He is the doctor.
• certain adjective uses , especially
  • modal verb-like uses with prepositions le, do, etc.
    e.g.: Ba mhaith le Pól an carr. = Paul would like the car.
  • adjectives of subjective assessment and of equivalence.
    e.g.: Is ionann iad = They are the same. Is maith sin! = That is good!
  • comparative (always with on of the copula forms is/ba or níos/ní ba)
    e.g.: an fear is mó = the biggest man (the man that is the biggest)
• origin- and ownership (with the prepositions as, de, le)
  e.g.: Is as Corcaigh sé = He is from Cork. Is le Pól an carr. = The car belongs to Paul.
• to emphasize single parts of speech and to loosen up the sentence structure (cleft- and pseaudo-cleft clauses )
  e.g.: Is é an fear a dhéanann na bróga = He's the man makes the shoes. (That's the man who makes the shoes.)
• full queries (questions with interrogatives). These always contain a copular construction, even if it's mostly not to be seen.
  e.g.: Cé a rinne sin? = Who did that? (Who is it, that did that?)

properties of the copula

• the copula exists only in 3 base forms:
  • present tense (in part, at the same time the future) is
  • preterite (same time imperfect, conditional) ba
  • subjunctive (rare) gura
• the copula does not exist in the imperative. The copula also has no "verbal noun".
  Instead, transcriptions with bí and the preposition i must be used. e.g. Bí i d'fhear! = Be a man!, bheith ina fhear = to be a man (see identificatory and classificatory clauses without the copula)
• copular forms are inflexible, and not conjugable (all forms are actually the 3rd person singular).
• after the copula, personal pronouns if the 3rd person in their "object form" follow (é, í, iad instead of sé, sí, siad)
• instead of "verbal particles " (ní, nach, go, etc.) compounds of the particle and copula [ 2 ] are used, that are often the same as the verbal particles in form.
• in the form of (rarer) conbinations with other words like conjunctions, prepositions etc.
• in the present tense, all copular forms and compounds thereof cause neither lenition nor eclipsis.
  in the preterite / conditional, the copula always causes lenition.
• certain different syntax rules apply.
  These follow also the basic syntax P-S-O:
  In an Irish sentence, the predicate comes first, then the subject, then the object (P-S-O)
  In copular clauses, the predicate is introduced by the copula. So: copula - predicate - subject. An object is not used.

[ 1 ]
The subject forms of the personal pronouns sé,sí,siad count as a combination of the copula is and the pronouns é,í,iad. This is how in every sentence with these pronouns the copula couples the predicate and subject. Also the relative form of the verb ending in -as in the combination with the copula is explained.
[ 2 ]
The claim that these are "compunds" or copula-"forms" is simplified:
In reality, they are often normal verbal particles by which the copula is simply omitted (e.g. ní insted of *"ní is").
The "missing" copular form is also the reason why that after the particles one doesn't lenite or eclipse: (ní maith liom not *"ní mhaith liom").
Although the copula mostla as the form (ba) is omitted after particles also in the preterite , the lenition caused by the absent ba remains: (e.g.: níor mhaith liom), so the instigator of the lenition is here actually not níor but the "missing in action " ba!
Real fusions are e.g. más (má + is) and those ending in -b, -bh (as a contrationc of ba, or. lenited bha), mostly only preceding a vowel: níorbh é an fear instead of *"níor bha é an fear"