Loftus, ó Lachtnáin, ó Lachtna This Gaelic surname derived from lachtna meaning ‘grey’. A sept who were chiefs of the district called the Two Bacs and of Glen Nephin in the Barony of Tirawley in Mayo. To be distinguished from the English surname and similar translations. In 1890 Loftus was principally found in Mayo, and the estimated number of bearers was 1,520. In the United States it is the 4,850th most numerous surname with an estimated 5,500 bearers.