Boyd’s Bible Dictionary:
(rain). A scoffing Arabian (Neh. 2:19; 6:1-2).
Concise Bible Dictionary:
An Arabian, who with Sanballat and Tobiah sought to hinder the rebuilding of Jerusalem (Neh. 2:19; Neh. 6:1-2). Called also GASHMU in ver. 6.
Jackson’s Dictionary of Scripture Proper Names:
rain