mach.se.yah is a proper name appearing as the grandfather in the family lines of Baruch and Seraiah.

The attested form is a proper name used in two genealogical identifications: Mahseiah is named as the father of Neriah and thus the grandfather of Baruch and Seraiah.

1. Proper name in family identification · dominant

   In Jeremiah 32:12, the form is tagged Noun · Proper and occurs in the identification of Baruch as son of Neriah, son of Mahseiah; the APB renders this family line within the transfer of the deed of purchase. In Jeremiah 51:59, the same proper-name form identifies Seraiah as son of Neriah, son of Mahseiah as he goes with Zedekiah to Babylon.

   Jeremiah 32:12Jeremiah 51:59

In the Anselm Project Bible: The APB presents the name in both verses within the phrase "son of Neriah son of Mahseiah." It confirms the genealogical setting rather than isolating the term beyond its use as a name.