pen·guin (pĕnggwĭn, pĕn-)
1. Any of various stout, flightless aquatic birds of the family Spheniscidae, of the Southern Hemisphere, having flipperlike wings and webbed feet adapted for swimming and diving, short scalelike feathers, and white underparts with a dark back.
2. Obsolete The great auk.
[Possibly from Welsh pen gwyn, White Head (name of an island in Newfoundland), great auk : pen, chief, head (from Middle Welsh penn; see pendragon in the Appendix of Indo-European roots) + gwynn, white; see weid- in the Appendix of Indo-European roots.]
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