Webster's 1828 Dictionary
SHELDUCK
n.A species of wild duck.
Webster's 1913 Dictionary
SHELDUCK
Shel "duck `, n. Etym: [Sheld variegated + duck. ] (Zoöl.)
Defn: The sheldrake. [Written also shellduck.]
New American Oxford Dictionary
shelduck
shel duck |ˈSHelˌdək ˈʃɛlˌdək |(male also sheldrake |ˈSHelˌdrāk ˈʃɛldreɪk |) ▶noun ( pl. same or shelducks ) a large gooselike Old World duck with brightly colored plumage, typically showing black and white wings in flight. [Genus Tadorna, family Anatidae: several species, in particular T. tadorna of Eurasian coasts, with white, greenish-black, and chestnut plumage. ] ORIGIN early 18th cent.: probably from dialect sheld ‘pied ’ (related to Middle Dutch schillede ‘variegated ’) + duck 1 .
Oxford Dictionary
shelduck
shelduck |ˈʃɛldʌk |(male also sheldrake |-dreɪk |) ▶noun ( pl. same or shelducks ) a large goose-like Old World duck with brightly coloured plumage, typically showing black and white wings in flight. ●Genus Tadorna, family Anatidae: several species, in particular T. tadorna of Eurasian coasts, with white, greenish-black, and chestnut plumage. ORIGIN Middle English (as sheldrake ): probably from dialect sheld ‘pied ’ (related to Middle Dutch schillede ‘variegated ’) + duck 1. The form shelduck dates from the early 18th century.
Sanseido Wisdom Dictionary
shelduck
shel duck /ʃéldʌ̀k /名詞 複 ~s, ~C 〘鳥 〙ツクシガモ (の雌 ).