Int. Standard Bible Encyclopedia GASHMU gash'-mu, gash'-moo (gashmu): A form of the name GESHEM (which see), found in Nehemiah 6:6 (compare Nehemiah 6:1), "And Gashmu saith it." According to BDB the same termination -u is found in Nabatean proper names.

Multi-Version Concordance Gashmu (1 Occurrence) Nehemiah 6:6 in which was written, It is reported among the nations, and Gashmu says it, that you and the Jews think to rebel; for which cause you are building the wall: and you would be their king, according to these words. (WEB KJV ASV DBY WBS YLT NAS)