Survey of English Place-Names

Historical Forms

• Morthwait, Morthwayt 1235–55,1292 Cockers 1279–81 QW

• Marethwait(e) 1547 FF

• Marthwaite 1547 FF

• Marthwett 1610 FF

Etymology

Marthwaite, Morthwait , Morthwayt 1235–55, 1292 Cockers, 1279–81 QW, Marethwait (e )1547 FF, 1625 Marthwaite 1547 FF, Marthwett 1610 FF. The earliest spelling appears to be OE  mōr 'moor' but, in view of the later development to Mar -, Mor - probably stands for ME  Moure - or Maure -, since Mar - would be a regular local development of the latter but not of mōr (cf. Phonol. § 8). The name would be similar to Mourethwait 191 supra (which also has Mor - and Maure - spellings) and mean 'ant-infested clearing' or 'Maur's clearing', from ON  maurr 'ant' (or the byname formed from it) and þveit .