The term apabhramsa was used in medieval Sanskrit texts to denote

In medieval Sanskrit usage the term “apabhramsa” referred not to social groups or ritual deviations but to vernacular dialectal varieties—literally a “corrupt” or non‑grammatical form—identified by Sanskrit grammarians as deviations from classical norms and representing the late Middle Indo‑Aryan stage that bridged Prakrit and the emerging modern Indo‑Aryan languages [2]. Scholarly and encyclopedic treatments describe Apabhramsha as a set of regional dialects that became a recognized literary medium (from about the 6th century onward) and which gradually evolved into distinct modern languages of North and West India; thus medieval texts use the term to denote early forms of some modern Indian languages rather than castes, ritual errors, or metres [2].

Sources

1. [1] https://www.britannica.com/topic/Apabhramsha-language
2. [2] https://www.sikhiwiki.org/index.php/Apabhramsha