In linguistic typology, split ergativity is a feature of certain languages where some constructions use ergative syntax and morphology, but other constructions show another pattern, usually nominative-accusative. The conditions in which ergative constructions are used varies among different languages. 
Nominative-accusative languages (including European languages, with the notable exception of Basque) treat both the actor in a clause with a transitive verb and the experiencer in a clause with an intransitive verb in the same way grammatically. If the language uses case markers, they take the same case. If it uses word order, it is parallel.
For example, consider these two English sentences:
The grammatical role of "Jane" is identical. In both cases, "Jane" is the subject.
In ergative-absolutive languages (including the Basque, Georgian, Greenlandic, and Mayan languages), there is a different pattern. The patient (or target) of a transitive verb and the experiencer of an intransitive verb are treated the same grammatically. If the two sentences above were expressed in an ergative language, "John" in the former and "Jane" in the latter would be parallel grammatically. Also, a different form (the ergative) would be used for "Jane" in the first sentence.
For example, in the following Inuktitut sentences, the subject 'the woman' is in ergative case (arnaup) when occurring with a transitive verb, while the object 'the apple' (aapu) is in absolutive case. In the intransitive sentence, the subject 'the woman' arnaq is in absolutive case.
In split ergative languages, some constructions pattern with nominative-accusative, and others with ergative-absolutive.
The split is usually conditioned by one of the following:
An example of split ergativity conditioned by the grammatical aspect is found in Hindustani (Hindi-Urdu), which uses ergative case for the subject in the perfective aspect with transitive verbs in the active voice, while the direct object takes absolutive case (which is the unmarked nominative case). However, in all other aspects (habitual & progressive), subjects appear either in the nominative or dative case (see: dative subjects).
In the following perfective sentence, the agent la?ke-ne (boy) is marked for ergative case, while the undergoer kit?b (book) is in unmarked nominative case. The verb khar?d? (bought) has the feminine ending -?, showing gender agreement with the undergoer kit?b (book).
lar?ke-ne kit?b xar?d? hai.
boy:MASC.SG.ERG book:FEM.SG-NOM buy:PRF.FEM.SG be:3P.SG.PRS
'The boy has bought a book'
In the corresponding imperfective (habitual aspect) sentence, the agent la?k? (boy) is in unmarked nominative case. The habitual participle form khar?dat? (buy) has the masculine ending -? and thus agrees with the agent la?k? (boy).
lar?k? kit?b xar?dat? hai.
boy:MASC.SG.NOM book:FEM.SG-NOM buy:HAB.MASC.SG be:3P.SG.PRS
'The boy buys a book'
Perfective constructions with certain VV (verb-verb) complexes do not employ ergative case marking (see: light verbs in hindi-urdu). In perfective constructions, the agent argument is ideally assigned with an ergative case; however in cases like the first example shown below that does not happen. This is because the explicator verb gay? (gone) which although undergoes semantic bleaching but still retains its intransitivity which does not allow for an ergative case assignment to the agent argument (i.e., nin?). This is why as shown in the second example below, VV complexes involving a transitive explicator verb (e.g., ph?k? "threw") can employ ergative case to agent arguments.
nin? ?m kh? gay?.
nina:FEM.SG.NOM mango.MASC.SG.NOM eat.NF go:PRF.FEM.SG
'Nina ate the mango.'
nin?-ne takiy? u?h? ph?k?.
nina:FEM.SG.ERG pillow.MASC.SG.NOM pick.NF throw:PRF.MASC.SG
'Nina (picked up and) threw the pillow.'
In transitive clauses, verbs are framed by a person marking prefix (called "set A" in Mayan linguistics) that expresses the subject, and a suffix that expresses the object (= "set B").
'You hug me.'
In intransitive clauses, the subject can either be represented by a set A-person marker, or a set B-person marker, depending on aspect.
In perfective aspect, Chol has ergative-absolutive alignment: the subject of the intransitive verb is expressed by a suffixed person marker, thus in the same way as the object of transitive verbs.
In imperfective aspect, Chol has nominative-accusative alignment: the subject of the intransitive verb is expressed by a prefixed person marker, thus in the same way as the subject of transitive verbs.
In Columbia River Sahaptin, the split is determined by the person of both subject and object. The ergative suffix -n?m occurs only for third-person subjects for which the direct object is in the first or the second person.
Another ergative suffix, -in, marks the subject in the inverse. Both subject and object are then always in the third-person.
Direct (same as above example):