from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A structuring property of the grammar of certain languages consisting in the differential treatment given to A (the subject of transitive verbs), in contrast to O (the object of transitive verbs) and S (the subject of intransitive verbs), which are treated similarly. This differential treatment may take the form of a special case marker (e.g., an affix or a particle) used with A but not with O or S, or of a specific agreement pattern (e.g., the verb may agree in person and number with A, but not with O and S).
From ergative + -ity. (Wiktionary)