From Proto-Slavic *tьšča.
тъ́ща • (tǎ́šta) f
- wife's mother, mother-in-law
- “тъща”, in Речник на българския език [Dictionary of the Bulgarian Language] (in Bulgarian), Sofia: Bulgarian Academy of Sciences, 2014
- “тъща”, in Речник на българския език [Dictionary of the Bulgarian Language] (in Bulgarian), Chitanka, 2010