1orn.zool.a bird, possibly so called because it inhabits moorland, or a variant form of morillon:
(
s.xiii2;
MS: s.xivm
)
Oiseals chauntaunz en cele arberie Escotoi de douce melodie [...] De charderole, praer, mortoun, Russinole, meerle [...]
76
(
MS: 1272-83
)
[A] esperver muer trainerez de cercele ou de mortun
89.4
mortun (s.xiii2)