Word Study
lemming
CIDE DICTIONARY
lemming, n. [Nor. lemming, lemende; cf. Sw. lemel, Lapp. lummik.].
Any one of several species of small arctic rodents of the genera Myodes and Cuniculus , resembling the meadow mice in form. They are found in both hemispheres. [1913 Webster]
" The common Northern European lemming (Myodes lemmus ) is remarkable for making occasional devastating migrations in enormous numbers from the mountains into the lowlands." [1913 Webster]
OXFORD DICTIONARY
lemming, n. any small arctic rodent of the genus Lemmus, esp. L. lemmus of Norway which is reputed to rush headlong into the sea and drown during migration.
Etymology
Norw.
For further exploring for "lemming" in Webster Dictionary Online